Article Understanding music-selection behavior via statistical learning: Using the percentile-Lasso to identify the most important factors Fabian Greb 1 , Jochen Steffens 2 and Wolff Schlotz 1 Abstract Music psychol ogical rese arch has either focused on indivi dual differ ences of music listeni ng behavior or investigat ed situati onal influe nces . The present stu dy addresses the ques tion of how much of pe ople’s list ening behavi or in daily life is due to individ ual differe nces and how much is att ributab le to situational eff ects. We aim ed to identi fy the most impo rtant factors of bot h levels (i.e., person- related and situ ational ) driving people ’s music selecti on behavior. Five hun dred eigh ty- seven par ticipan ts repor ted thr ee sel f-sele cted ty pical music lis tenin g situ ations . For eac h situ ation, they ans wered ques- tions on situ ati onal cha racte rist ics, fun ctio ns of mu sic liste nin g, and ch aract eristi cs of th e music selec ted in th e spec ific situ ation (e. g., fas t - slow , simpl e - com plex) . Parti cipan ts als o repor ted on sev eral pe rson- relate d var iable s (e.g. , musical tas te, Big Five persona li ty dime nsions ). Due to the large numbe r of varia bles mea sured , we imple mente d a stati stic al learn ing met hod, perc enti le-La sso, for variabl e sel ection, whic h preven ts overf itti ng and opt imize s model s for the pr edict ion of uns een data. Mo st of the var ian ce in musi c selec tion be havio r was at tributa ble to di ffere nce s betw een situ ations , while indi vidua l diffe rence s accoun ted for much le ss varian ce . Situat ion-s peci fic funct ions of music li steni ng most consi stentl y expl ained which ki nd of mu sic peopl e sel ected , follo wed by the degre e of at tenti on pai d to the mu sic. Ind ivid ual diffe ren ces in musi cal ta ste most con sist ently acc oun ted for pe rson- relat ed diff erence s in musi c selecti on behav ior, where as the infl uence of Bi g Five pers onalit y was very weak . These res ults sho w a de tail ed patter n of factor s influ encing th e selec tion of musi c with spec ific cha ract eristic s. They cle arly em phasi ze the impor tance of si tuati onal ef fects on musi c liste ning behav io r and sug gest sh ifts in wid ely-u sed expe rime ntal de signs in la borato ry-ba sed re search on mu sic list ening behav ior. Keywords daily life, statistical learning, lasso regression, situational influences, music listening behavior, music selection behavior, percentile-lasso Submission date: 11 August 2017; Acceptance date: 8 January 2018 “ What music does to people at d ifferent ti mes, why they choose to listen to it so much, and why they choose a particular type of music while engaged in a particular activity – all of these are important unanswere d questions” (Konec ˇ ni, 1982, p. 500) Although Vladimir Konec ˇ ni wrote the statement above in 1982, many o f these questio ns remain unanswered. Rese arc h inv es tiga ti ng mu sic- list en ing be ha vio r in dai ly life usually follows one of two traditions, either focusing on individual differences (e.g., functions of music listening, music preferences), or investigating situational influences. The present study aims to bridge this gap by investigating the relative significance of variables from both the person- related and situational domains simultaneously. From this 1 Max Planck Institute for Empir ical Aesthetics, Frankfurt am Main, Germany 2 Audio Communication Group, Technische Universita ¨ t Berlin, Germany Corresponding author: Fabia n Greb, De part ment of M usic, Max Planc k Insti tute for Empir ical Aesthetics, Gru ¨ neburgweg 14, 60322 Frankfurt am Main, Germany. Email: [email protected] Musi c & Scie nce Volume 1: 1–17 ª The Author(s) 2018 DOI: 10.1177/2059204318755950 journals.sagepub.com/home/mns Creative Commons CC BY: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). l compr ehens ive persp ect ive, we aim to identi fy the most important variables underlying music selection using meth- ods from statistical learning theory to prevent overfitting and maximize predi ctive accuracy (Chapman, Wei ss, & Duberstein, 2016). Recent technical innovations allow the listener to listen to any kind of music in almost any situation, transforming music-listening behavior on two levels. First, engagement with music has become highly individual, and second, peo- ple now have the opportunity to listen to music in almost any everyday situation. These developments provide new opportunities for studying individual differences and situa- tional influences of music-listening behavior, reflecting the major questions of the person-situation debate in personal- ity psychology (see Fleeson & Noftle, 2008 for review). Following a synthesis approach, research on human beha- vior in daily life, including music listening, can potentially provide mor e reliable results and mode ls by consider ing both levels of influence. In music psychology, fe w studies on music-listenin g behavior to date have integrated both person-related and situational levels of influe nce. The following paragraph outlines the findings of those studies that did consider both levels. Krause and North (2017) have used person-related (e.g., sex, age, importance of music) and situational vari- ables (e.g., time of day, activity) to predict music listening in a certain situation, how much choice people had in what they heard, how participants l iked the music t hey were listening to, how engaged they were, and how arousing they perceived the music to b e. Randall and Ri ckard (2017) developed a two-level model of personal music listening (i.e., listening via headphone s) with regard to affective cha nges a ttribu ta ble t o music l ist enin g. They fo und th at affective changes due to music are almost entirely deter- mined by the situation, whereas individual differences have only marginal effects. Furthermore, Greb, Schlotz, and Steffens (2017) explored the most important person- relate d and situational v aria bles predicting functions of music li stening (i.e., why a pers on lis tens to mus ic in a certain situation). By quantifying the relative weight of individual and situational influences, they showed that music-listening functions are primarily attributable to char- acteristics of the situation. This predominance of situa- tional influences on the goals and effects of music listening gives rise to a number of new questions. For example, what music do people select in order to accom- plish their goals in a specific situation? What are the key variables ultimately driving individuals’ music choices? Randall and Ric k ar d (2 01 7) s h ed s om e li gh t on t h es e qu es - tions by predicting the perc eived emotional qualities of music using situational and pe rson-rela ted variables, but their characterization of mus ic chos en by individu als was limited to the affective dimensions of valence and arousal. However, music perce ption comprises mor e character is- tics, and these might be differe nt ially influenced by situa- tional and person-related var iables (e.g., the tempo of a piece of music might be differentially perceived based on situational characteristics) . Consequently, the present study focused on predicting a broader variety of subjec- tive characteristics of music selected in daily life situa- tions, such as tempo, melody, an d complexity, by integrating variables relate d to listener, situation, and function of music listening. Person-related variables Previous research has found that demographic characteris- tics of listeners, their personality, musical taste, strength of music preference, and musical training are all potentially relevant variables contributing to music-listening beha- viors. Demographic variables such as sex or age have con- sistently been shown to relate to music-listening behavior in daily life. For example, males under 34 years of age were found to visit live music events more often than females (Eventbrite & Media Insight Consulting, 2016) and also to purchase and download music more often (Aguiar & Mar- tens, 2013). With regard to the functions of music listening, research has consistently revealed that females tend to use music for affective functions (e.g., expressing feelings and emotions), coping, and enhancement ( Boer et al., 2012; Chamorro-Premuzic, Swami, & Cermakova, 2012; Kuntsche, Le Mevel, & Berson, 2016), while men tend to use music for cognitive or intellectual reasons (Chamorro- Premuzic e t al., 201 2). Youn g pe ople ( 10–34 y ears old) show a clear tendency to access recorded music via digital channels such as YouTube, digital streaming, downloads, or online ra dio (E ventbr ite & Medi a Insigh t Consult ing, 2016) and are more likely to access copyright-infringing music (Avdeef, 2012; International Federation of the Pho- nographic Industry, 2016). In contrast, people older than 30 years of age are more likely to use legal download sources, to buy CDs, and to listen to music on a CD player or via radio (Avdeef, 2012). Ferwerda, Yang, Sc hedl, and T kalcic (2015) demon- strated seve ral rel ation ships betw een pers onalit y and the way individuals browse and select music from streaming services. For example, individuals scoring high on Open- ness to experience are more likely to choose mood taxo- nomies offe red by str eaming serv ices to brow se through music collections, while individuals scoring high on Con- scientiousness are more likely to use activity taxonomies. In addition, numerous studies linking personality dimen- sions (Big Five) with music al taste and pref erences f or certain musical styles indicate an indirect relation between personality dimensions and music-selection behavior (e.g., Greenberg, Baron-Cohen, Stillwell, Kosinski, & Rentfrow, 2015; Rentfrow, Goldberg, & Levitin, 2011; Rentfrow & Gosling, 2003). This indirect relation is supported by Dunn, de Ruyter, and Bouwhuis (2012), who found positive cor- relations between individuals’ musical taste and their actual listening behavior in daily life. Also, Greb et al. (2017) showed that fans of blues and jazz music tend to 2 Music & Science listen to music for intellectual stimulation, while fans of techno and electronic dance music tend to listen to music to move and enhance their well-being. Individuals who con- sider music to be an important part of their life tend to seek situations that involve music and are also more engaged with music when listening to it (Krause & North, 2017). Furthermore, Elpus (2017) showed that people who received school-based musical training and education are more likely to engage in musical activities such as playing an instrument or singing, while Stratt on and Zalanow ski (2003) found students majoring in music listened to a greater diversity of music than non-music majors. Situational variables Conceptualizing a situation is notoriously difficult; defini- tions and terminologies consequently vary between differ- ent research fields and even within the same field (for reviews see Rauthman n, 2015 or Rauthmann, Sherman, & Funder, 2015). Rauthmann et al. (2015) proposed a tax- onomy that differentiates bet ween situational cues (i.e., measurable situational properties such as time or weather), situational char acteristics (i.e., t he individual perc eption and experience of situational cues), and situational classes, which are abstract groups or types of situations based on similar cues or characteristics. In terms of this taxonomy, musi c ps ycho logy re sear ch o n sit uati on al in fluen ces h as mostly focused on cues such as location, activity, presence of others, or time of day. Previous research has shown that the listening location influences goals and functions of music listening (North, Hargreaves, & Hargreaves, 2004). In addition, the effects of music listeni ng and the experience of musi c vary by loca tion t ype ( Kra use & No rth, 2 017; Kr aus e, No rth, & Hewitt, 2014). Furthermore, Krause and North (2017) found that type of location predicts the presence of music as well as perceived arousal of the music. Recent research has highlighted a person’s activity while listening to music as the most influential situational variable for explaining how people use music in a specific situation (Greb et al., 2017). In addition, activity has been shown to be an impor- tant predictor of the presence of music, a person’s engage- ment with music, and a person’s experience of the arousing qualities of music in a given situation (Krause & North, 2017). Finally, Randall and Rickard (2017) found a nega- tive association between traveling and perceived valence as well as a positive association between housework and the perceived arousal of the music heard. Research has consis- tently shown that the functions of music listening vary depending o n the presence of ot hers (Greb et al., 2017; North et al., 2004; Rana & North, 2 007). For example, people te nd to use mus ic to pas s the time or to supp ort concentration when they are alone, but they use music to create a particular atmosphere when together with friends (Greb et al., 2017; North et al., 2004). These findings sug- gest that the presence of others also has an influence on the music chosen in a specific sit uation. Mo reover, several stu die s have s ugg es ted th at fu nct ion s of mus ic l iste nin g vary by time of day (Krause et al., 2014; North et al., 2004). For example, North et al. (2004) indicated that music is more likely to be used to help pass time during the workday (8:00 a.m. to 4:59 p.m.) than during the eve- ning (5:00 p.m. to 11:00 p.m.). In another study by Krause and North (2017), participants were less likely to encounter music as the day progressed from morning to evening. It remains unclear whether these variations in the functions of music listening are also associated with specific musical choices, thus prompting the current study. Besides the above-mentioned situational cues, there are also several concomitant person-related variables influ- enced by s ituations. F or exampl e, current m ood as well as goals and functions of music listening have been shown to strongly vary by situatio n and also to impact musical choices. Recent daily life research has found a positive association between initial affective state at the moment a person decides to listen to music and perceived affective characteristics of the music selected, while controlling for a broad set of potential covariates (Randall & Rickard, 2017). While these results are su pported by findings of several studies that reported similar mood-congruent music selection effects (Ska ˚ nland, 2013; Thoma, Ryf, Mohiyed- dini, Ehlert, & Nater, 2012), they are challenging several theories and an enormous body of research. This research states either that music is selected to moderate arousal to an optimal level (Konec ˇ ni, Crozier, & Doob, 1976; Konec ˇn i & Sargent-Pollock, 1976) or that it is used to reach certain arousal-state goals, such as becoming energized du ring exercise (North & Hargreaves, 2000; for an overview of these opposing theories see Hargreaves & North, 2010). In general, further research is required to clarify the relation- ship between momentary mood and the music selected in daily life. Music li steni ng serv es a nu mber o f functi ons be yond mood regulation (for an overview, see Scha ¨ fer, Sedlmeier, Sta ¨ dtler, & Huron, 2013). These functions have been shown to predominantly vary between situations (Greb et al., 2017) and to be associated with specific music styles (North et al., 2004). Randall and Rickard (2017) found that functions can be used to make predictions about the affec- tive qualities of music selected at a certai n time. More specifically, they found a negative association between the use of cognitive functions of music listening and the per- ceived (positive) valence of the music selected. In order to understand the music selected to fulfill the various functions of music listening, the present study aimed to predict the characteristics of the music selected by considering the above-discussed listener and situation variables. We had three specific objectives: 1. To investigate the relative influence of person- rela ted an d sit ua tion al f act ors on m usic -se le ctio n Greb et al. 3 behavior (i.e., estimating between- and within- person variance). 2. To control for a broad multivariate set of potentially influencing factors (i. e., the variables discussed above, for an overview see Figure 1) as they occur in reality in contrast to previous studies that predo- minantly have focused on bivariate relations of spe- cific variables and music-listening behavior. 3. To identify key person-related and situational vari- ables that reliably predict music-selection behavior in daily life using a statistical-learning approach that avoids overfitting of the statistical model. To this end, we conducted an online survey asking par- ticipants to sequentially report three self-chosen listening situations typically occurring in their daily lives. For each listening situation, participants answered questions related to the situation, the music heard, and the functions of music listening. In addition, we measured multiple person-related variables (e.g., personality, musical taste). Using statistical learning methods for variable selection Given the numerous potentially relevant variables dis- cussed abo ve, we were faced with several challenges. Research consistently has shown that common model selection procedures such as stepwise procedures (includ- ing fo rwar d, back ward , comb ine d forw ard-b ackwa rd, all possible subset selection) lead to overestimation of regres- sion coefficients (Chatfield, 1995; Steyerberg, Eijkemans, & Habbema, 1999) and to selection of irrelevant predictors (Derksen & Keselman, 1992). These problems, known as overfitting , are more likely to occur with decreasing sample Person Functions of music listening Situation Music-selection behavior • Intensity of music preference • Musical taste (6) • Personality traits (Big Five) • Musical training (GMSI.3) • Age • Gender • Intellectual stimulation • Mind wandering & emotional involvement • Motor synchronization & enhanced well-being • Updating one‘s musical knowledge • Killing time & overcoming loneliness • Activity (11) • Presence of others (4) • Possibility of choice (5) • Importance of mood • Mood (valence, arousal)* • Time of day (5) • Degree of attention calming–exciting* less melodic–very melodic less rhythmic–very rhythmic slow–fast sad–happy known–unknown* simple–complex peaceful–aggressive like not so much–like a lot* Figure 1. Variables measured in the online survey. Person-related variables were measured once, while functions of music listening, situation, and music-selection behavior were reported for each of three situations. Numbers in parentheses indicate the number of categories or dimensions a variable included. * Indicates variables which have been excluded from the main analysis due to problematic distributions or too many missing values (see data analysis for details). 4 Music & Science size ( n ) to predictor ( p ) ratio (Babyak, 2004; Derksen & Keselman, 1992). In general, as the number of predictor variables included in a model grows, so does the likelihood of finding relationships in sampled observations which are not present in the actual population (Babyak, 2004). Over- fitting relates to the tendency of statistical models to mis- takenly fit sample-specific noise (for reviews see Babyak, 2004; Hawkins, 2004) and might be one of the factors unde rly ing the r epli cati on cris is in ps ych olo gy (Ya rkoni & Westfall, 2017). An o verfitted model is not g oing to produce reliable predictions on unseen data as it contains relations which are only present in the sample used to esti- mate the model and not in the general population. There- fore, avoiding overfitting when estimating stati stical models was one of our core aims and is one of the primary objectives of the field of statistical learning. In recent years, statistical learning theory has developed several techniques to optimize models for the prediction of unseen data and to reduce overfitting. More specifically, regression regulari- zation methods (also referred to as shrinkage methods) are often used in the context of the problem (Gareth, Witten, Hastie, & Tibshirani, 2015) . The Lasso, originally pro- posed by Tibshirani (1996), has become a popular approach to variable selection in regression. It places a penalty on the regression coefficients, shrinking them all towards zero and sets some coefficients exactly to zero. The Lasso features a tuning parameter l that controls the amount of shrinkage applied to the coefficients. The value of this tuning para- meter is chosen using K -fold cross-validation, a technique of randomly splitting the set of observations into K folds of approximately the same size. Subsequently, K -1 folds (the training set) are used to estimate a statistical model, while the remaining fold (the validation set) is used to compute the mean squared error ( MSE ). In the regression setting, the MSE is given by MSE ¼ 1 n X n i ¼ 1 ð y i ^ y i Þ 2 ð 1 Þ where ^ y i is the prediction for the i th observation, and n is the number of observations. The MSE will be small if pre- dictions are very close to the true value of y , and it will be large if predictions and true responses differ substantially. This procedure is repeated K times until every fold has been used as a validation set and results in K estimates of the test error, MSE 1 , MSE 2 , ... , MSE K . The K -fold cross-validation error is given by CV ð K Þ ¼ 1 K X K k ¼ 1 MSE k ð 2 Þ The selection of the optimal tuning parameter l opt via cross-validation is based on a number series of l values (grid). This grid should cover a range from zero, indicating no shrinkage and all predictors included in the final model, to l max , a value of l for which all coefficients are set to zero and the model is empty. During the cross-validation proc ess, a K -fold c ross -va lid atio n err or is c alc ula ted f or each l -value of the grid. Finally, the l -value that yielded the smallest cross-validation error is chosen as l opt . The Lasso can therefore be used for variable selection and does not impose the limitations of stepwise selection methods (Tibshirani, 1996; Whittingham, Stephens, Bradbury, & Freckleton, 2006). As we needed to include numerous specific potentially relevant variables to predict an ou tcome, we had to address a high-dimensional regression problem (Chap- man et al., 2016). In addition, we were not basing hypoth- eses on specific predictor-outcome associations. Therefore, we used a specific Lasso regression procedure that is suitable for this application as it is robust against overfitting, optimized to make predictions on unseen data, and has been specifically developed for multiple observations within clusters. Method Sample Participants were recruited via mailing lists of German univ ersit ies, pos ters at Go eth e Unive rsity Fr ankf urt, an d Facebook. Respondents could enter a lottery to win a 15 Euro voucher for Amazon (chance of winning 1 in 10) as an incentive. In total, 945 people began the study. Sub sequently, 176 participants discontinued participation during the description of the first situation, 133 while describing the second situation, and nine while reporting the third and last situation. Additionally, 40 respondents did not follow the instructions, reporting multiple situations in the first text field. Consequently, we excluded these participants ( N ¼ 358; 38 % of those who started the study) from the analyses. This exclusion rate is comparable to that of other online studies (e.g., Egermann & McAdams, 2013). The remain- ing 587 participants (58 % female) included in the study had a mean age of 25.4 years ( SD ¼ 7.0). This final sample was characterized by rather minor deviations within one SD from age-spec ific aver age T -values based on a norm sample using a short version of the Big Five Inventory (Rammstedt, 2007). Despite being statistically significant (one-sample t -tests: all p s < .01), deviations of sample means were minor for Agreeableness ( T ¼ 51) and Extra- version ( T ¼ 49), while average Conscientiousness ( T ¼ 44) and Neuroticism ( T ¼ 44) scores wer e moderately lower, and Openness scores moderately higher ( T ¼ 56) than the norm-based average. Design and measures The questionnaire covered fo ur areas: the situation, the functions of music listening in the specific situation, music Greb et al. 5 characteristics, and personal information (see Supplemen- tal material online). The situation section asked several questions about the participants’ ability to choose the music, presence of others, and time of day (see Supplement Section A). The music individuals listened to in specific situations was characterized via seven-step bipolar rating scales. Specifically, we asked for familiarity (unknown–known), liking (I do not like–I like a lot), and seven musical char- acteristics, namely: calming – exciting , less melodic – very melodic , less rhyt hmic – very rhythmic , slow–fast , sad – happy , simple–complex , peaceful – aggressive . These musi- cal charact eristics were com piled by a group of ex perts, including musi cologists, music psyc hologists, and audio engi nee rs , wit h the o bj ecti ve o f eas ily de sc ri bing mu sic in daily life. For t he purpose of avoiding unsystematic variance in the data, participants alternatively could check unspecific/I do not know for each of these items (see Supplement Section B). Functions of music listening were measured by factor scores on five factors de scribed by Greb et al. (2017). These factors are based on 22 items capturing a wide range of functions of music listeni ng th at could vary across different sit uations (see Supplement Section C), labeled Intellectual Stimulation , Mind Wandering & Emotiona l Involv ement , Motor Synchronization & Enhanced Well- Bein g , U pdati ng O ne’ s Mu sica l Kno wl edg e ,a n d Killin g Time & Overcoming Loneliness . As previous research has indicated that a listening experience might involve multiple functions (e.g., Greasley & Lamont, 2011), we assessed all functions for each situation. In addit ion, we ga thered the followi ng perso n-rel ated information: gender, age, Big Five personality traits using the BFI-10 (Rammstedt, Kemper, Klein, Beierlei n, & Kovaleva, 2013), and intensity of music preference mea- sured by a six-item inventory (Scha ¨ fer & Sedlmeier, 2009). We also assessed musical training using the third scale of the Gold-MSI consisting of seven items (Schaal, Bauer, & Mu ¨ llensiefen, 2014) and musical taste via an inventory described in Greb et al. (2017) that captures six taste dimensions: Blues & Jazz (blues, jazz, funk, soul, reggae), Techno & EDM (techno, EDM, house, rap/hip-hop), Other Cultures & Latin (other cultures, Latin, world music, clas- sical), Volksmusik & Schlager (German “Volksmusik” and German “Schlager”), Pop (pop), and Rock & Metal (rock, metal). This inventory also allows participants to indicate if they are not familiar with a certain style of music. For these styl es, no l iking r ati ngs wer e co llect ed (s ee Su pple ment Section D). For a s chematic overvi ew of all vari ables reported in the present study, see Figure 1. Procedure The data were collect ed through the same survey use d by Greb et al. (2017). While Greb e t al. (2017) inve stigated the effect of personal and situational factors on why peo- ple listen to music in a specific situation, the current investigation is focused on the effect of situational and personal factor s on the actual music that is selecte d in a specific situatio n. Therefore, the present study uses another subset of situations and additional variables ( i . e . ,m u s i cs e l e c t e di na s p e c ific situation) that were not analyzed by Greb et al. (2017). Data were collected online ( browser-based) through Unipark/ EFS Survey soft ware (Q uestback Gm bH). After clicking the participation link or scanning a QR code from a poster, participants were redirected to the online survey. The welcome page informed participants about the general procedure and focus of the study, the voluntariness of par- ticipation, their ability to discontinue the study at any time, and the opportunity to take part in a lottery to win a vou- cher. Thereafter, the task of the survey – to sequentially Table 1. Explanation and descriptive statistics of the 11 activity categories. Activity while listening Description % of total activities Being on the move Situations in which the main activity was being on the move (e.g., by car, subway, or bike). 30.3 Housework Situations in which the main activity was doing any kind of housework (e.g., washing up, cleaning, getting ready). 15.5 Working & studying Situations in which the main activity was either working, learning, or studying. 13.8 Others Situations which could not be coded to one of the other categories. 11.0 Pure music listening Situations in which the main activity was listening to music only. 7.3 Relaxing and falling asleep Situations in which the main activity was relaxing, getting new energy, or trying to fall asleep. 6.9 Exercise Situations in which the main activity was exercising or doing sports. 5.8 Party Situations in which the main activity was celebrating or dancing in a club or disco (dancing which was mentioned in a training context was coded as Exercise). 4.5 Coping with emotions Situations in which the main activity was coping with own emotions. 2.5 Making music Situations in which the main activity was playing or making music. 1.3 Social activity Situations in which the main activity was interacting with others (e.g., cooking and eating with friends, or playing with friends). 1.2 Note. Each situation described in free response format ( N ¼ 1,582) was classified into one of the activity categories. 6 Music & Science describe three self-selected situations in which participants typically listen to music – was explained. First, participants were asked to describe the specific situation in a concise sentence with as much as detail as necessary. Then, parti- cipants answered questions regarding the situatio n, the music, and functions of music listening in that specific situation (see Suppleme nt Sections A to C). These three sections were successively answered for each of the three situations. Subsequently, participants reported on person- level variables (Appendix Section D). Finally, if desired, they could provide their email address to take part in the raffle to win the Amazon voucher. Data analysis As our aim was to analyze music-selection behavior, we excluded all situations in which participants indicated that they did n ot have any c ontrol ab out the mus ic pres- ent in a given situation (excluded categories: possibility of choice “ no” [85 situations] and “ unspecif ic” [94 situations]). The final dat a include d 1,582 s ituations from 586 p articipa nts. As reported in Greb et al. (2017), each individu al sit- uation description was classified into one of 11 activity categories, and listening lo cation was d iscarded due to high correla tions between ac tivity and location categories. Table 1 provides the activity cate gory labels, descriptions, and relative fre quencies. Based on th e high numb er of miss ing valu es, which were due to the response option of unspecific/I don’t know , we excluded valence (400 missing values, 25 % of total data) and arousal (342 missing values, 22 % of total data) from the major analysis. We calculated separate analyses investigating the effects of valence and arousal because we expected them to be important variables. The results are reported separately. In addition, we excluded familiarity, liking and calming–exciting from the analysis due to skewed distributions. This finally resulted in six outcome variables considered in the present analysis: less melodic – very melodic , less rhythmic – very rhythmic , slow – fast , sad – happy , simple–complex , peaceful – aggressive . F or each outcome variable, we excluded all cases in which partici- pants selected unspecific/I don’t know . Situational cues, functions of music listening, and char- acteristics of the music heard were measured three times per person, creating a two-level structure of measures (situations) nested within persons. We therefore used multi- level linear regression modeling, as it allows the inclusion of time-varying (i.e., situation-related) predictors and the analysis of unbalanced designs, while at the same time acc ounti ng f or no n-in de pen dence o f ob ser vati ons wi th in subjec ts. Ca tego ric al vari ab les wer e inc lude d as d ummy variables (coded as 0, 1). All within-person predictors (i.e., all responses that were measured separately for each situation) were centered at each person’s mean to avoid any confounding effects with between-person variability (Enders & Tofighi, 2007). As one of our aims was to identify the most important variables predicting music-listening behavior (i.e., musical characteristics people choose to listen to) and due to the high number of independent variables (Figure 1) we used a percentile-Lasso regression method for generalized linear mixed models. Recent research has shown that the optimal value of the tuning parameter l ( l opt ) chosen by cross- validation (and therefore also the final model) is extremely sensitive to the fold assignment of the cross-validation pro- cedure (Krstajic, Buturovic, Leah y, & Thomas, 2014; Roberts & Nowak, 2014). To overcome these limitations, we implemented the percentile-Lasso method proposed by Robe rts an d Nowa k (201 4). This met ho d deal s wit h the problem of fold sensitivity by using repeated cross- validation, leading to less variation in l opt . In detail, the percentile-Lasso selects l opt from a set of optimal values (derived from each cross-validation cycle) by calculating the y -percentile of this set. In most circumstances, y ¼ 0.95 produces good and reliab le results (Roberts & Nowak, 2014). In addition, the percentile-Lasso allows the imple- mentation of the “one-standard-error” (1- SE ) rule to select l opt . The main purpose of the 1- SE rule, as proposed by Hastie, Tibshirani, and Friedman (2009), is to choose the most parsimonious model whose accuracy is comparable with the best model. The 1- SE rule is applied by selecting the largest value of l whose corresponding cross-validation error is within one standard error of the minimum cross- validation error as l opt . In our d ata a nal ys is, we r epe ate d 10 0 ten -fo ld cr os s- val idat ion s. Fo r ea ch cro ss- val idat io n cyc le, th e op timal value of l according to the 1- SE rule was calculated. From this set of 100 potentially optimal values, the 95th percen- tile was selected as the final l opt . For each outcome vari- able, we determined the value of l for whic h all coefficients were set to zero ( l max ) by successively increas- ing l by 1 until the condition was met. 1 Then, an individual l max value was taken as the maximum grid value for each model. We used a grid length of K ¼ 100 and an exponen- tial form for the grid to achieve higher resolution of values towards 0. More specifically, we used the following grid for all models: l k ¼ 1 2 exp k K 1 ln ð 2 l max þ 1 Þ 1 with k ¼ 0 ; 1 ; 2 ; :::; K 1 ð 3 Þ where l k denotes the k -th element of the grid, K is the grid length, and l max the value of l where all predictors were set to zero. As suggested by Tibshirani (2013), we calculated the null space of each predictor matrix and found the null vector for all matrices. This ensured that the Lasso solu- tions were unique. We applied this procedure to each outcome variable separa tely, leadi ng to six final models. All calculations Greb et al. 7 were pe rformed u sing t he glmmLa sso packag e (Grol l, 2017) within the development environment R-Studio (RStudio Team, 2015) of the software R.3.0.2 (R Core Team, 2015) . For ou r cat egor ical v aria bles (w hic h were entered as dummy-coded variables), we used a group Lasso estimator as proposed by Groll and Tutz (2014). It applies the same amount of shrinkage to all dummy variables that constitute one categorical variable (e.g., the variable time of day is constituted by early morning, morning, noon, afternoon, evening, and night). Therefore, the Lasso either completely includes a categorical variable (i.e., all consti- tuting dummy variables) or completely excludes it from the final model (for more detailed information see Meier, Van De Geer, & Bu ¨ hlmann, 2008; Yuan & Lin, 2006). Estima- tion of p -values for non-zero coefficients was based on re- estimation and Fi sher scoring as implemented in glmmLasso (Groll, 2017). In accordance with Roberts et al. (2016), we took the nested structure and the number of data points per partici- pant into account when randomly splitting the data into 10 folds (i.e., into training and validation sets) for cross- validation. We decided to randomly split our data at the level of the individual (Level 2). Therefore, any training and validation set contained measurements from the same person, and the models were optimized to predict values of unseen individuals. This approach does not allow the inclu- sion of random effects of Level 1 predictors but should lead to highly reliable fixed effects. We calculated the repeated cross-validation error as the mean of the cross-validation error across 100 repetitions as a measure of fit index. This index is small if the predicted responses are close to the true responses. In addition, we calculated marginal R 2 as pro- posed by Nakagawa, Schielzeth, and O’Hara (2013) after re-estimating the final m odel using the lme4 (Bates, Maechler, Bolker, & Walker, 2015) and the MuMIn (Bar- ton, 2016) packages. Marginal R 2 indicates the proportion of variance explained by the fixed effects. Results Situational vs. person-related influences on characteristics of music selected Intra-class correlation coefficients (ICCs) based on an intercept-only m odel for each musical characteristic are shown in Table 2. Intra-class correlation coefficients indi- cate the amount of variance attributable to person-related and situational levels. For the six musical characteristics studied here, ICCs varied between .09 for fast–slow and .32 for peaceful–aggressive . The ICC for fast–slow indicates that between-person differences accounted for 9 % of the varia nce, wh ile wi thin-per son dif ferenc es be tween s itua- tions accounted for 91 % of the variance. Across all models, between-person differences on average accounted for 23 % and within-person differences between situations for 77 % of the variance, signifying high variability within individuals and the potentially important role of situational characteristics in the music selections of individuals. Predicting characteristics of music selected Figure 2 shows the coefficient paths of the percentile-Lasso and l opt based on repea ted cross -validation for the s ix musical characteristics, illustrating how coefficients of pre- dictors tend towards zero with a growing amount of shrink- age (i.e., with growing l ). When a predictor is set to zero, it is eliminated from the model. When l max is reached, all coefficients are set to zero. For the musical characteristics melodic and rhythmic , only one predictor was selected, while multiple predictors were included for the other mod- els. The development of regression coefficients also illus- trates their interdependence. Mor e specifically, some coefficients rise when other coefficients are set to zero. Table 2 shows the maximal grid values ( l max ), the opti- mal tuning parameter l opt , the repeated cross-validation error, marginal R 2 , and the estimations of regression para- meters for predictor variables included in the six models. The repeated cross-validation error varied between 1.45 for sad – happy and 1.97 for simple – complex , and marginal R 2 ranged from .35 for slow – fast to .04 for melodic . Whereas the cross-validation error of sad – happy indicates the best model in terms of predictions on unseen data, the model slow – fast had the highest proportion of explained variance, with the largest marginal R 2 . The number of selected vari- ables fell between 1 for melodic and rhythmic and 13 for complex . On the level of situational variables, functions of music listening were included in all six models, degree of attention in four models, and activity and presence of oth- ers in three models. Variables most often included on the person-related level were musical taste (included in three models) and intensity of music preference (included in two models). In contrast, perso nality traits and gender w ere only present in one model each, while age and musical traini ng wer e not in clu ded in a ny model. The foll owin g sections provide a more detailed overview of the predictors included in each of the six models separately for situational and person-related levels. Situational variables The fi ve fa ctor s of fu ncti on s of mus ic list en ing w as the on ly gr oup of va ri able s inc lu de d in al l six mo de ls. Wh en pa r tici - pa nts re port ed li sten in g to mu si c for inte lle ct ual st imu lat io n, th ey ten ded to li st en to more m elod ic , les s fast , less ha pp y, mor e comp lex , and less ag gr essi ve musi c. Mi nd wan de ring and emotional involvement was related to less happy and more complex music. Participants tended to choose more rh ythm ic , fast er , ha ppi er, an d mo re ag gres si ve mu sic w he n wanting to move and enhance their well-being. Updating on e’s mu si cal kn owl ed ge led to fa ster , happ ie r, less co m plex , an d mo re aggr es sive mu si c ch oice s. S lowe r and les s ag gr es- si ve mu sic wa s us ed to pa ss th e tim e and ov erco m e lone lin es s. 8 Music & Science Table 2. Multilevel estimations of within- and between-subject effects for musical characteristics. Predictors selected by the percentile- Lasso with repeated 10-fold cross-validation (CV) (see text for details). Parameter Estimate ( SE ) less melodic– very melodic a less rhythmic– very rhythmic b slow–fast c sad–happy d simple– complex e peaceful– aggressive f ICC .28 .22 .09 .18 .29 .32 l opt 328.84 421.55 89.30 103.28 62.82 52.20 l max 376 560 771 436 575 602 Repeated 10-fold CV error 1.93 1.82 1.49 1.45 1.97 1.94 Marginal R 2 .04 .09 .35 .23 .28 .24 Situational predictors Fixed effects Activity Being on the move .15 (.33) .05 (.35) .22 (.31) Housework –.03 (.10) –.05 (.11) –.05 (.11) Working and studying –.26 (.13)* –.18 (.14) –.38 (.13)** Pure music listening .10 (.16) –.19 (.16) .18 (.17) Party –.23 (.19) .29 (.27) .39 (.21) Relaxing and falling asleep –.79 (.17)*** –.38 (.18)* –.80 (.17)*** Exercise .42 (.16)** –.01 (.17) .92 (.17)*** Coping with emotions –.40 (.24) –1.90 (.23)*** .81 (.26)** Making music –.16 (.38) –.45 (.42) .20 (.37) Social activity .42 (.33) .25 (.33) .10 (.32) Presence of others Alone –.13 (.08) –.23 (.08)** –.27 (.08)** Others present and no interaction .03 (.12) –.09 (.13) –.30 (.13)* Others present and interaction .15 (.23) .23 (.25) –.13 (.22) Possibility of choice Yes .27 (.10)** Radio –.30 (.18) Concert .30 (.24) Importance of mood Degree of attention .06 (.03)* –.03 (.03) .07 (.03)** .06 (.03)* Time of day Early morning .03 (.09) Morning –.03 (.09) Noon .13 (.11) Afternoon .19 (.09)* Evening –.24 (.08)** Functions of music listening Intellectual stimulation .59 (.06)*** –.49 (.07)*** –.09 (.08) .61 (.07)*** –.25 (.07)*** Mind wandering and emotional involvement –.26 (.08)*** .30 (.07)*** Motor synchronization and enhanced well-being .79 (.05)*** .91 (.06)*** .73 (.07)*** .59 (.07)*** Updating one’s musical knowledge .38 (.06)*** .30 (.06)*** –.25 (.06)*** .18 (.06)** Killing time and overcoming loneliness –.13 (.07) –.14 (.07)* Person-related predictors Intensity of music preference .09 (.04)** .15 (.04)*** Musical taste Blues and Jazz –.20 (.04)*** Techno and EDM .14 (.04)*** –.07 (.05) Other cultures and Latin (continued) Greb et al. 9 With regard to the activities included in the six models, the analyses revealed several findings. Music reported for working or studying was less fast, less happy, and more peaceful. For r elaxing and fa lling asleep, participants reported listening to slower, less happy, and less aggressive music. While exercise was associated with faster and more aggressive music, coping with emotions was related to less fast, less happy, but also more aggressive music. Participants reported a tendency to listen to slower, less happy, and more peaceful music when alone. Situations in which others were present (without communication) showed a similar pattern, differing only in a faster tempo of the music in comparison to that chosen when alone. Given freedom of choice, participants were likely to sele ct mo re comp le x musi c. In c ont rast, l is tenin g to th e radio was associated with less complex music choices. Moreover, th e de gree of at ten ti on part ic ipan ts re port ed to pa y to th e mus ic wa s re late d to f as ter, l ess ha pp y, m ore co m- pl ex, an d mor e ag gr essi ve m usic . How ev er, th e re lati on sh ip between the degre e of attention and the happine ss of the mu sic di d no t reac h si gn ific anc e in th e re -es tim ati on st ep . The time of day was only included in the predictive model of peaceful – aggressive , indicating that listening to m u s i ci n t h ea f t e r n o o nw a sr e l a t e dt om o r ea g g r e s s i v e music choices, whereas music listening in the evening was associated with less aggressive music. As mentioned in the data analysis section, we repeated the complete analyses with the data set, including valence and arousal to determine whether they would be selected by the perce nti le-L asso. Th is ana lysis re vea led va lence a nd arou sal to be inc lud ed in tw o mode ls. Re porte d va lence (positive mood) at the moment of the decision to listen to music was associated with happier ( b ¼ .21, p < .001) and more complex music ( b ¼ .08, p ¼ .02). When participants reported relatively high arousal when deciding to listen to music, they tended to select faster ( b ¼ .10, p < .001) or more aggressive music ( b ¼ .07, p ¼ .02). Person-related variables Musical taste factors were included in three out of the six models, revealing several individual differences. In detail, participants who endorsed enjoying Blues and Jazz tended to listen to slower music, while fans of Techno and EDM rep orte d a tende ncy to li sten to fa ster and le ss com plex music. Whereas fans of Pop and Volksmusik and Schlager tended to listen to less complex music, partic ipants who reported liking Rock and Metal were disposed to listen to music with increased tempo, higher complexity and more aggressivenes s. Participan ts with high intensity of mus ic preference reported listening to faster and more complex music. The personalit y traits o f Openness to exper ience, Agr eea blen es s, an d Neu roti cis m rema in ed in o ne mo del only, predicting the selection of simple versus complex music. Specifically, participants scoring high on Openness to experience tended to listen to more complex music, while those with high Agreeableness and Neuroticism scores leaned to wards les s comple x music. Fin ally, men reported listening to more aggressive music than women. Discussion This stu dy invest iga ted the relat ive in fluen ce of perso n- related and situational factors on music-selection behavior Table 2. (continued) Parameter Estimate ( SE ) less melodic– very melodic a less rhythmic– very rhythmic b slow–fast c sad–happy d simple– complex e peaceful– aggressive f Volksmusik and Schlager –.15 (.05)*** Pop –.33 (.05)*** Rock and Metal .10 (.04)* .15 (.05)** .24 (.05)*** Personality traits Openness to experience .09 (.06) Conscientiousness Extraversion Agreeableness –.13 (.05)* Neuroticism –.14 (.05)** Age Sex g .56 (.10)*** Musical training Random effects SD intercept .86*** .84*** .63*** .70*** .81*** .91*** Note . SE ¼ standard error; ICC ¼ intra-class correlation coefficient; CV ¼ cross-validation; EDM ¼ electronic dance music; SD ¼ standard deviation. a n ¼ 1,318 observations within 547 persons. b n ¼ 1,330 observations within 547 persons. c n ¼ 1,270 observations within 537 persons. d n ¼ 1,196 observations within 525 persons. e n ¼ 1,210 observations within 524 persons. f n ¼ 1,262 observations within 536 persons. g 0 ¼ female; 1 ¼ male. * p < .05. ** p < .01. *** p < .001 10 Music & Science in daily life by integrating a broad set of potentially impor- tant variables in comprehensive models. A statistical learn- ing procedure (percentile-Lasso) optimized for predicting unseen data was used to identify the key variables of both levels influencing the selection of music with defined char- acteristics by individuals within specific, comprehensively characterized situations. Fin ding s demon strat ed that t he characterist ics of music select ions predominantly varied within persons, that is, between situations. However, both the relative contribution of situational a nd individual effects as well as the number of predictor variables contri- buting to music selection varied, indicating that some char- acteristics mainly vary between situations while others are more affected by individual differences. Notably, functions of music listening was the only group of variables that was included in each model, and hence can be seen as the most important situational variables with regard to a broad set of characteristics of music sel ected in specific situations. Although less broadly re presented, music al taste factors was also found to be an important group of variables explaining individual differences in music-selection beha- vior in three out of six models. Taken together, 29 situa- tional and 14 person-related p redictors were found to contribute to the prediction of unseen data, clearly reflect- ing the importance of varianc e attributable to situatio nal differences. Due to the fact that all models were optimized to make predictions on unseen persons, the effects found should be highly reliable. The significance of situational factors found in the pres- ent study is consistent with current research showing that functions of music listening and affective changes in response to music are mainly influenced by the listening situation (Greb et al., 2017; Randall & Rickard, 2017). For example, the ICC of .18 we found for the sad – happy out- come variable is close to findings from a recent experience sampling study by Randall and Rickard (2017), who reported an ICC of .14 for valence of music selected ( neg- ative – positive ). This highly situational selection behavior might be explained in part by recent technological devel- opments that provide music listeners with high degrees of freedom for listening to all kinds of music in almost any situation. The detailed patterns uncovered by the present investi- gation suggest that people’s music-selec tion behavior is mainly driven by the functions of music listening, degree of attention a person pays to the music, current activity, and the presence of others while listening. These findings are partly consist ent with Randall and Rickard (2017), who demonstrated strong associations between functions of music listening, activity, and the actual music selected. Randall and Rickard (2017) also found cognitive reasons for listening – which are broadly comparable to our happy melodic rhythmic aggressive complex fast -3 -2 -1 0 1 2 3 4 5 6 7 -3 -2 -1 0 1 2 3 4 5 6 7 -3 -2 -1 0 1 2 3 4 5 6 7 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 log( λ ) Coefficients β ^ Figure 2. Coefficient paths of the percentile-Lasso models for six musical characteristics. The x-axis shows log of l ; the y-axis shows penalized regression coefficients. Each line represents a specific regression coefficient. Dummy variables pertaining to one variable share the same color. Starting from the left, l is very small (virtually no penalization) and all predictors are included in the model. Moving from left to right the amount of shrinkage increases and coefficients tend towards zero. Predictors are eliminated when they hit the horizontal “0” line. The optimal value of the tuning parameter l ( l opt ) is shown by the vertical dashed line. Greb et al. 11 intellectual stimulation factor – to be associated with the selection of less positive/happy music. Ou r finding that musical taste was an important vari- able explaining indivi dual difference s of music-sele ction behavior complements fin dings by Dunn et al. (2012) who reported positive correlations between liking for musical styles and listening durations for these styles. Our results indicate that music al taste (measured via lik- ing for musical styles) is also rela ted to preference s for certain characteristics of music listened to in daily life. Nevertheless, the amoun t of variance attribu table to between-person differences for all musical characteristics was lower than the amount of v ariance attributable to situational differen ces. T his contradicts the common belief that individuals’ mus ic-selection behavior is mainly driven by musical taste. The fact that Big Five personality traits were only selected in one out of six models indicates a rather weak association between personality traits and music-selection behavior in daily life. This finding is in line with a recently conducted meta-analysis by Scha ¨ fer and Mehlhorn (2017) showi ng th at Bi g Fiv e pers ona lity tr ait s can not su bsta n- tially account for variance between individuals in musical taste and preferences. We found associations only between personality traits and the selection of complex music. Our finding that Openness to experience is positively associated with the selection of complex music is consistent with Scha ¨ fer and Mehlhorn (2017) who demonstrated a positive correlation between Openness and the liking for more com- plex musical styles. The current s tudy foc used on mus ical chara cteristics selected in specific situations. Hence, we could not deter- mine which style of music people selected in everyday life, so further research is needed in this area. This would aid in examining how people differ in their selection with regard to different styles and also check for within-style variability (e.g., Rentfrow et al., 2012). It may be that a person con- stantly listens to a favorite style of music but selects music with different musical characteristics within that style based on the situation. Nevertheless, Rentfrow et al. (2012) conclude that individual differences in musical pre- ferences are largely based on sonic characteristics of the music. From this, one would also expect large individual differences with regard to musical characteristics selected in daily life. This is contrary to our findings, which show rather small individual variations. Results from our separate analysis of the role of current mood on music-selection behavior complement the find- ings by Randall and Rickard (2017), who demonstrated that people generally tend to select mood-congruent music. We found positive assoc iations between valence (positive mood) and the selection of happier and more complex music, as well as between arousal and the selection of faster and more aggressive music. These four musical character- istics go beyond the analysis of music selection by Randall and Rickard (2017) that limited its measurement to perceived valence an d a r ou sa l o f t h e m us ic . N e ve rt he l es s, the characteristics found t o be associated with current mood in our stu dy can be inte rpreted i n the framework of valence and arousal: happier music is likely to be per- ceived as more positive, while faster, more aggressive, and more complex music is likely to be perceived a s more arousi ng. From thi s perspe ctive, our results reflec t mood- congruent selection of music. In contrast to Randall and Rickard (2017), however, not all of our outcome variables were associated with curr ent mood. For example, current mood was not related to the selection of more melodic or more rhythmic music in our analysis. This might be due to our more differentiated measu rement of characteristics of music selected ( six musical character istics) compared to perceived valence and arousal of the music as used by Randall an d Rickard (201 7). In genera l, our find ings pro- vide a detailed picture of the relationship between current mood and music selected and largely sup port the notion that people select mood-congr uent music. Th is conclusion is also supported by the findin g of a negative association between coping with emotio ns a n dt h e s e l e c t i o no fl e s s happy music in our study . Interestingly, person-related variables were included in jus t thr ee mo de ls ( slow – fast , simple – comple x , peaceful – aggressive ). As demonstrated by ICCs, the models of music complexity and aggressiveness showed the strongest asso- ciations with individual differences, and the model predict- ing selection of fast music showed the highest amount of variance within individuals (i.e., a minimum of between- person variance). Thi s raises the question as to w hy no pers on-r elated p redic to rs were selec ted in th e remai ning models ( less melodic – very melodic , le ss rhythmic – very rhythmic , sad – happy ) despite considerable between- person variance in these outcomes. It is likely that highly relevant traits for these outcome variables were not repre- sented by our measures of individual differences. For example, there is some evidence that trait empathy is asso- ciated wit h the selection of sad music (e.g., Vuoskoski, Thompson, McIlwain, & Eerola, 2012) and that alexithy- mia may explain individual differences in the perception of emotions expressed by music (Taruffi, Allen, Downing, & Heaton, 2017). Another remarkable result was the varying number of predictor variables included in each model. The extreme parsimoniousness of the models predicting the selection of very melo di c or ve ry rh yt hmic mus ic mig ht in di cat e an important role of individual differences. Some situational associa tions fo r tho se two v ariable s might va ry betw een individuals, whic h could be accounted fo r by including random slope parameters in the mixed- effects regression models. These individual deviations from the overall slope means might be best explained by cross-level interactions (i.e., person x situation interaction effects). For instance, individuals scoring high on Extraversion might tend to lis- ten to more complex music while working and studying, while persons scoring low on Extraversion might tend to 12 Music & Science select simpler music (Furnham & Allass, 1999). We decided against the inclusion of random slopes and inter- action effects on the basis of very limited numbers of obser- vations within participants in our sample (max. three data points per participant), which would make model estima- tion unstable and potentially unreliable. Henc e, future research could benefit from the inclusion of random slopes, implying that a larger num ber of situations should be sampled per individual. The variation of repeated cro ss-validation errors and marginal R 2 values across the different models clearly shows that high R 2 values are not necess arily associated with small repeated cross-va lidation errors (i.e., good pre- dictions on unseen individuals). For example, while the model predicting the selection of slow – fast music reveal ed the highest mar ginal R 2 of .35, the model show- ing the best prediction on unseen individu als ( sad – happy ) revealed a marginal R 2 value of .23. In addition, the two models melodic and rhythmic , both of which contained only a single predictor, yielded comparable or even slightly better repeated cross -validation errors than the two models predicting complex and aggressive music (both containing several pr edictors). On one hand, this highlights the importance and reliability of the single pre- dictors in the models melodic an d rhythmic . O n the oth er hand, it might indicate slightly overfitted models for com- plex and aggressive , despite our use of the 1- SE rule th at protects against overfitting. In addition, the present investigation demonstrated that innovative statistical learning techniques can effectively be used to inform psychological research. We believe that the analysis of intensive longitudinal data from studies of daily life that incl ude la rge numbe rs of pote ntia lly in teract ing variables would strongly benefit from such techniques. For example, using cross-validation methods could lead to higher reliability of variable selection due to avoidance of overfitting. The concept of optimizing models by pre- dicting unseen data is a core strength of statistical learning procedures. The use of s uc h methods prevents th e researcher from overfitting by optimizing R 2 and therefore is likely to result in more precise estimation of effects. In addition, R 2 values represent better estimations of the true values in the general population of interest (for an over- view, see Yarkoni & Westfall, 2017). This characteristic of statistical learning procedures partially explains the rather low marginal R 2 values of some of our models, and is likely to be a consequence of more precise estimations. As mentioned in the introduction, defining what consti- tutes a situation is a difficult endeavor. Following the tax- onomy pro posed by R authmann et a l. (2015 ), curre nt research clearly shows the significance of situational char- acteristics (i.e., the individual perception and experience of situational cues) for t he prediction of human behavior (Sherm an, Rauthmann, Brow n, Serfass, & Jones, 2015). On a higher level, situational classes form abstract groups or types of situations based on similar cues or characteristics. This study, as well as most of the other studies dealing with situational influences on music listen- ing, used measurements of situational cues and character- istics to investigate situational effects. However, it might be more beneficial to attempt to cluster situational cues and characteristics into situational classes. By combining sev- eral situational cues and characteristics, such classes could provide a more abstract and condensed form of situational variable. These could then be used to make predictions about music-listening behavior, thereby savin g the researcher from interpreting seemingly endless single asso- ciations between cer tain situational vari ables and beha- vioral outcome variables of interest. In addition, some situations are normatively related to specific functions of music listening and to specific music characteristics. For example, music in a dance club is intended to evoke move- ment, and it is very likely to be rhythmic and fast. From this perspective, a more abstract level of situation, as given by situational classes, would provide an opportunity to clearly differentiate such normative situations from situations in which people have greater freedom to choose music. Our study comes with a number of limitations. First, our data result from retrospective self-report and are therefore vulnerable to memory effects, social desirability, and other biasing factors. This also implies that ecological validity might be limited, even though the reports were based on daily life situations. As mentioned earlier, we collected a maximum of three data points per participant. While this allowed u s to esti mat e withi n-su bjec t effe cts (i. e., s itua- tional effec ts), additional data points would have l ed to more precise estimations with potentially higher represen- tativeness for participants’ daily lives. This limitation was deliberate in order to minimize the time required to com- plete the online survey and avoid threats to data quality. Although we asked participants to describe listening situa- tions th at typically oc cur in thei r daily live s, we do not know how re prese ntativ e the three s ituation s were of a participant’s actual behavior. Hence, future research should replicate our findings using methods with higher ecological validity and better representativeness of situations, such as ambulatory assessment or related methods (Hektner, Schmidt, & Csikszentmihal yi, 2007; Randal l & Rickard, 2013; Shiffman, Stone, & Hufford, 2008; Trull & Ebner- Priemer, 2014). Such methods usually collect momentary data in particip ants’ daily lives; momentary reports ar e virtually unaffected by memory effects and provide inten- sive longitudinal data with potentially high representative- ness (Mehl & Conner, 2012). In addition, the use of such methods will provide more complete situational data com- pared to our approach of measuring recollections of typical situations, as we had to offer an unspecific response option for some variables, which resulted in a relatively high pro- portion of missing values. Second, the present study relates to the measurement of music chara cteristi cs, which wa s based on part icipants’ rep orts. As th e pe rcep tion o f the se ch arac teris ti cs mi ght Greb et al. 13 vary between individuals (e.g., Taruffi et al., 2017), future research should broaden the measurement of music selected by supplementar y measures, such as objective musical feat ures obtained by music- information retriev al (e.g., loudness, tempo) or musical styles selected. This could offer further insights and would provide answers to additional questions, such a s: Do subjectively reported characteristics correlate with objectively derived character- istics of music selected? Do fans of certain styles of music predominant ly listen to thei r favorite styles in ever yday life? However, individual music selection is based on indi- vidual perception. Therefore, subjec tive measurements such as those applied in our study should be complemented, but still included, in future s tudies investigating m usic- selection behavior. Third, due to the fact that, to the best of our knowledge, no package or software solution exists that is able to per- form a Lasso regression on a multivariate multilevel model, our approach does not account for covariations between our six outcome variables. Hence, it is important to mention that our results of modeling predictors of different musical characteristics are based on independent models. A single multivariate model might lead to slightly different results. Taken together, the present stud y demonstrates that music-selection b ehavior strongly varies between s itua- tions within indivi duals. This situational variability was best explained by situation-specific functions of music lis- tening, while musical taste was found to be the most impor- tant variable explaining differences on the individual level. In general, a better understanding of which music people listen to in different situations to accomplish certain listen- ing goals might help experimental researchers to properly select music for the investigation of specific functions or effects of music listening. Future research should integrate situational variables into research design in order to pro- vide optimal conditions for investigating specific effects of music as well as to inc rease the reliabil ity and external validity of results. Acknowledgements We would like to thank Andreas Groll for his advice in using his glmmLasso package. We also thank Melanie Wald-Fuhrmann and the three reviewers for their critical reading of earlier versions of the manuscript. Finally, we are thankful to Claudia Lehr, Ingeborg Lorenz, and Mia Kuch whose support has been of value for the realization of the study. Contributorship FG and JS designed the study and collected data. FG developed and performed the statistical analysis in conjunction with WS. FG wrot e the fir st dra ft of the ma nus crip t. Al l author s inte rpre ted data, reviewed and edited the manuscript, and approved the final version of the manuscript. Declaration of conflicting interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The authors received no financial support for the research, author- ship, and/or publication of this article. Peer review Amanda Krause, University of Melbourne Faculty of VCA and MCM. David Greenberg, City University of New York. Philippe-Aubert Gauthier, Groupe d’Acoustique de l’Universit ´ e de Sherbrooke, Mechanical E ngineering, Universit ´ ed e Sherbrooke. Supplemental material The supplemental material is available online with the article. Note 1. It is also possible to estimate l max using the dual norm (for a discussion see Bach, 2011). 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