Psychometric Properties of Identity Style Inventory-5 Indonesian Version: Factor Structure, Reliability, and Criterion Validity

This research evaluated the psychometric properties of the Identity Style Inventory-5 (ISI-5) Indonesian version using 763 adolescents aged 18-21 years. The evaluation process was carried out by examining the factor structure, reliability, and criterion validity using confirmatory factor analysis, composite reliability, and by correlating with other measuring instruments. The analysis results indicated that the ISI-5 version's factor structure with three factors of identity style and one identity commitment is fit with the data and has good internal consistency. The correlation between this version and other measuring instruments proves that it has fairly good criterion validity. The results showed that the ISI-5 Indonesian version is a valid and reliable instrument for measuring Indonesian adolescents' identity style and commitment.

Identity formation is a complex process in which humans develop a clear and unique view of themselves and their identities. This concept, which is considered as the significant task of adolescent development, namely identity achievement and confusion, was first developed by Erik Erikson (1950Erikson ( , 1968. As an effort to operationalize Erikson's (1950) concept, Marcia (1966Marcia ( , 1993) developed a status model using two dimensions of identity formation, namely commitment and exploration. The concept developed by Erikson (1950) and Marcia (1966) has promoted several studies on the development and expansion of the identity formation concept (Schwartz, 2001). A typical extension is the identity style model (Berzonsky, 1989). Berzonsky (1989) developed the identity style model as an individual approach in exploring various alternatives and making decisions regarding identity. This model is based on the way individuals construct and revise their sense of identity (Berzonsky, 1988(Berzonsky, , 1990(Berzonsky, , 1993. Berzonsky stated that, when individuals construct themselves, they use cognitive structures to form knowledge procedures and schemes from experiences of interacting with the physical and social environment (Berzonsky, 1993). Cognitive structures owned by individuals are used to solve problems and make decisions regarding identity issues (Berzonsky, 2004b(Berzonsky, , 2005. Therefore, this model analyzes individuals' cognitive strategies during the identity formation process by exploring alternatives, overcoming conflicts, and making decisions regarding identity (Berzonsky, 1989(Berzonsky, , 2004a(Berzonsky, , 2011.

Identity style model
This model consists of three identity formation strategies, namely informative, normative and diffuse-avoidant styles (Berzonsky, 1989(Berzonsky, , 2004a(Berzonsky, , 2011. Informative style is a strategy that indicates individuals are actively seeking, processing, and evaluating relevant information during the identity formation process . Those with this style tend to possess a critical attitude, skeptical of their views, open to new information, and flexible to feedback, contrary to their chosen identity (Berzonsky, 2008;Berzonsky et al., 2013;. Therefore, they try to evaluate and change their chosen identity Berzonsky & Kuk, 2005;Duriez et al., 2012). Furthermore, individuals with informative styles define their personal attributes such as values, goals, and standards (Berzonsky, 1994;Berzonsky et al., 2003).
The normative style is an identity formation strategy that indicates individuals are internalizing as well as automatically obeys the significant norms and expectations of others during the identity formation process (Berzonsky, 2011;Luyckx et al., 2007;. Furthermore, they tend to adapt to traditional views, have a low tolerance for uncertainty, and exonerate themselves from information that threatens their values and beliefs (Berzonsky et al., 2013;Duriez et al., 2012;. Therefore, individuals with normative style try to maintain their chosen identity (Berzonsky & Kuk, 2005;Berzonsky et al., 2013;. Furthermore, those with this style define themselves based on group attributes such as religion, family, and country (Berzonsky, 1994;Berzonsky et al., 2003) The diffuse-avoidant style is an identity formation strategy that indicates individuals are trying to delay and avoid making decisions about identity until situational demands require the process (Berzonsky & Kuk, 2005;Luyckx et al., 2007;. Individuals with this style tend to accommodate views and react to changes in situational demands and consequences Duriez et al., 2012;. They try to choose an identity that fits the situation, hence the chosen identity tends to be unstable and changing (Berzonsky & Ferrari, 2009;Berzonsky & Kuk, 2005;Berzonsky et al., 2013). Furthermore, individuals with diffuse-avoidant styles define themselves as social attributes such as reputation and popularity (Berzonsky, 1994;Berzonsky et al., 2003). Berzonsky (1989) developed the Identity Style Inventory (ISI) to determine the identity style. The ISI measures both identity style and commitment as an addition to the sub-scale. Identity commitment is an individual's loyalty to the chosen beliefs, values, and goals . Berzonsky (2003) explained in detail the three commitment functions in the identity formation process. First, commitment motivates individuals to have direction and purpose of being able to face setbacks and failures. Second, it has an evaluative function that aids in decision making and problem-solving, thereby facing various alternative identities. Finally, commitment functions as self-confidence in the chosen identity alternative.
ISI-5 has been validated and used by Muttaqin and Ekowarni (2016) to measure identity style in Indonesian adolescents. However, it is still limited to the informative, normative, and diffuse-avoidant style subscales and excluded in the commitment subscales. Furthermore, the psychometric property testing is valid for the factor structure and composite reliability. According to previous studies, the ISI-5 measurement model had a factor load ranging from 0.588 to 0.936 with CFI, GFI, and RMSEA coefficients of 0.962, 0.965, and 0.067, respectively. Additionally, it has a composite reliability coefficient of 0.826, 0.705, and 0.723 for the informative, normative, and diffuse-avoidant style subscales, respectively.
Limited information regarding the ISI-5 psychometric properties as a whole promotes the need to carry out a further evaluation. Therefore, this research tested the internal structure and reliability of the ISI-5 composite and examined the criterion validity. This test was carried out on the measuring instrument by correlating it with other constructs that are theoretically related (Bandalos, 2018;Furr, 2011). Information regarding the criteria validity is useful for evaluating the accuracy of the measuring instruments. Berzonsky (1989) stated that an identity style is an approach chosen by individuals during the formation process. Each approach processes information related to identity formation differently (Berzonsky, 1989(Berzonsky, , 2004a(Berzonsky, , 2011. Irrespective of the fact that each of them has different characteristics, the meta-analysis results carried out by Bosch and Card (2012) stated that there is a relationship between identity styles. Subsequently, the informative and normative styles have a positive relationship and are negatively related to the diffuseavoidant style Berzonsky & Kuk, 2000;Berzonsky & Papini, 2015;Crocetti et al., 2013;. In terms of commitment, informative and normative styles have a positive relationship, while diffuse-avoidant styles have a negative relationship (Berzonsky, 2008;Berzonsky et al., 2013;. Although informative and normative styles are positively related to commitment, the approaches used during decision-making on identity are different. Furthermore, the informative style improves commitment based on exploring various relevant information, while the normative style is based on significant obedience to others (Berzonsky, 2008(Berzonsky, , 2011Berzonsky & Kuk, 2005;Berzonsky et al., 2013).

The relationship of identity style to the identity dimension, self-esteem, and psychological well-being
Previous studies reported that a relationship exists between identity style and identity dimensions. Individual characteristics with an informative style that seek the process and evaluate relevant information related to the reevaluation and change in existing identities (Berzonsky, 2011;Berzonsky et al., 2011;Berzonsky & Kuk, 2005;Duriez et al., 2012). This shows that the informative style has a positive relationship with commitment, in-depth exploration, and reconsideration of commitment (Crocetti et al., 2009;Muttaqin & Ekowarni, 2016;Zimmermann et al., 2012). Characteristics of a normative style that tries to internalize and comply with others' expectations significantly causes individuals to maintain and deepen their existing identities (Berzonsky, 2011;Berzonsky & Kuk, 2005;Berzonsky et al., 2013;. Therefore, this style has a positive relationship with commitment and in-depth exploration (Crocetti et al., 2009;Muttaqin & Ekowarni, 2016;Zimmermann et al., 2012). Furthermore, individual characteristics with a diffuse-avoidant style that try to delay and avoid identity formation make them change their existing identities according to situational demands (Berzonsky, 2008;Berzonsky et al., 2007;Berzonsky & Kuk, 2005;. This suggests that the diffuse-avoidant type has a negative relationship with commitment and in-depth exploration and a positive relationship with reconsideration of commitment (Crocetti et al., 2009;Muttaqin & Ekowarni, 2016;Zimmermann et al., 2012).
Optimal identity formation makes adolescents have positive psychosocial development, and with identity confusion, they tend to possess negative psychosocial development (Schwartz, 2007;Schwartz et al., 2011). One of the indicators that help individuals to be able to achieve optimal identity formation is the development of positive self-esteem Sandhu & Singh, 2012;Schwartz et al., 2009). Regarding the identity style model, some studies have discovered that self-esteem is positively related to informative, normative, and commitment styles, which are negatively related to the diffuse-avoidant style (Crocetti et al., 2009;. Optimal identity formation make individuals develop positive psychological wellbeing (Ritchie et al., 2013;Schwartz et al., 2011). The concept of multidimensional psychological well-being put forward by Ryff (1989) consists of autonomy, environmental mastery, personal growth, positive relations with others, purpose in life, and selfacceptance. Consequently, when related to this dimension, informative style and commitment considered indicators of optimal identity formation have a positive relationship. Conversely, the diffuse-avoidant style, which is a less optimal identity formation, has a negative relationship with the six psychological well-being dimensions (Berzonsky & Cieciuch, 2016;Crocetti & Shokri, 2010;Vleioras & Bosma, 2005). The normative style specifically has a unique relationship with these dimensions based on the cultural context. However, the studies carried out in Iran (Crocetti & Shokri, 2010) and Poland (Berzonsky & Cieciuch, 2016) stated that normative style is positively related to the psychological well-being dimensions and negatively related to autonomy and personal growth (Berzonsky & Cieciuch, 2016).

Research purposes
This research aimed to evaluate the ISI-5 Indonesian version's psychometric properties used to measure identity style and commitment. Firstly, it examined the factor structure using confirmatory factor analysis (CFA). Secondly, the research tested the reliability of the ISI-5 Indonesian version using the composite reliability formula. Finally, the criterion validity was examined by correlating the factor scores from the ISI-5 Indonesian version subscale with identity, self-esteem, and psychological well-being dimensions.

Research participants
The research participants were selected based on the following criteria: 1) adolescences aged 18 to 21 and 2)male and female undergraduates of higher education at a private university in Surabaya. The data collection method used was the accidental sampling technique, which involves meeting participants at the end of the lecture session and determining their willingness to participate in the research. The participants were made to understand that it was not compulsory to participate in the research. However, those willing to participate agreed to the informed research consent and were asked to fill out an online questionnaire using Google Form. Therefore, this research was carried out involving 763 adolescents aged 18 to 21 years (M = 20.060, SD = 1.111). Participants consisted of 256 (33.6%) males and 507 (66.4%) females from big (63.8%), and small cities (31.1%) as well as villages (5.1%). The majority of the participants (89.1%) live with both biological parents while the rest live with their biological mothers (6.4%), biological fathers and stepmothers (1.4%), biological mothers and stepfathers (1, 3 %%), biological father (0.9%) and others (0.8%).

Research instrument
Identity style Identity Style Inventory Version 5 (ISI-5; Berzonsky et al., 2013) consisting of 36 items was used to measure identity style, such as informative (9 items, e.g., "When facing a life decision, I try to analyze the situation in order to understand it"), normative (9 items, e.g., "I think it is better to adopt a firm set of beliefs than to be open-minded"), diffuseavoidant (9 items, e.g., "I try to avoid personal situations that require me to think a lot and deal with them on my own"), and commitment (9 items, e.g., "I am emotionally involved and committed to specific values and ideals"). It uses five response options ranging from 1 (not at all like me) to 5 (very much like me).

Identity dimension
The Utrecht-Management of Identity Commitments Scale Indonesian version (U-MICS; Crocetti et al., 2008;Muttaqin, 2017) consisting of 26 items are used to measure the identity dimensions in the education domain and its relationships with friends. U-MICS consists of 3 identity dimensions, namely commitment (10 items, e.g., "My education allows me to face the future with optimism"), in-depth exploration (10 items, e.g., "I make a lot of effort to keep finding out new things about my best friend"), and reconsideration of commitment (6 items, e.g., "I often think that a different education would make my life more interesting"). In addition, five response options ranging from 1 (strongly disagree) to 5 (strongly agree) were used.
Self-esteem Rosenberg Self-Esteem Scale (RSES; Rosenberg, 1965) consists of 10 items to measure selfesteem (e.g., "I feel that I'm a person of worth, at least on an equal plane with others"). This tool adopted four response options ranging from 1 (strongly disagree) to 4 (strongly agree).

Psychological well-being
Psychological Well-Being Scales (PWBS; Ryff, 1989) consisting of 42 items is used to measure the participants' psychological well-being. PWBS consists of 6 dimensions, namely autonomy (7 items, e.g., "My decisions are not usually influenced by what everyone else is doing"), environmental mastery (7 items, e.g., "In general, I feel I am in charge of the situation in which I live"), personal growth (7 items, e.g., "I have the sense that I have developed a lot as a person over time"), positive relations with others (7 items, e.g., "I sometimes feel as if I've done all there is to do in life"), purpose in life (7 items, e.g., "I sometimes feel as if I've done all there is to do in life"), and self-acceptance (7 items, e.g., "I like most aspects of my personality"). Furthermore, six response options ranging from 1 (strongly disagree) to 6 (strongly agree) were used.

Data analysis procedures
Identity Style Inventory Version 5, Rosenberg Self-Esteem Scale, and Psychological Well-Being Scales were adapted in the Indonesian version using guidelines from the International Test Commission (Hambleton, 2005). The measuring instrument adaptation stage includes translating from English to Indonesian, checking the translation accuracy, and translating back into English. Each stage was carried out by two independent and dependent translators and two reviewers. Finally, the trial test was carried out to determine the participants' understanding of the measuring instrument in the Indonesian version.
The factor structure validity of the ISI-5 Indonesian version was tested with confirmatory factor analysis using the IBM SPSS AMOS 21 program with maximum likelihood estimation (Arbuckle, 2012). The measurement model is developed by creating item parceling because the scale has more than five items per construct and was tested on a large number of samples (Bagozzi & Heatherton, 1994). Based on prior research recommendations (Crocetti et al., 2009;Crocetti & Shokri, 2010;Zimmermann et al., 2012), the identity style measurement model was prepared using nine parcels. Each model consists of three parcels containing three items. The identity commitment measurement model is prepared by creating four parcels. Three of them consist of two items, while the remaining one has three.
The criterion validity from the ISI-5 Indonesian version was tested with the correlation analysis using the SPSS 21 program. This analysis was carried out by correlating the factor scores from the ISI-5 with those of other measuring instruments obtained from the confirmatory factor analysis estimation. Therefore, this research also developed a measurement model for the identity, self-esteem, and psychological wellbeing dimensions. The identity dimension measurement model was developed with nine parcels, with each consist of two parcels containing three items and one parcel containing four items. The self-esteem measurement model is structured by creating four parcels with two containing three items, while the other two contain two items. The psychological well-being measurement model involves eighteen parcels, and each dimension consists of three parcels with three items.
The precision indices such as Goodness of Fit Index (GFI), Comparative Fit Index (CFI), and Root Mean Square Error of Approximation (RMSEA) are used to evaluate the measurement models. Consequently, when the GFI and CFI coefficients are greater than or equal to 0.9 (Bentler & Bonett, 1980;Cole, 1987), the RMSEA coefficient is less than 0.1 (Cudeck & Browne, 1992). The measurement model is declared to have satisfactory accuracy. Furthermore, based on recommendations from Hair et al. (2014), a composite reliability coefficient of more than 0.7 implies that the measurement model has a satisfactory internal consistency. This coefficient was calculated using the total factor load's quadratic formula divided by its square plus the total measurement errors (1squared of the factor loads).

Results
The confirmatory factor analysis results indicated that all measurement models are consistent with the data, as shown in Table 1. This is because all the models have GFI and CFI coefficients greater than 0.9 and RMSEA coefficients less than 0.1. In detail, the ISI-5 Indonesian version measurement model has a load factor ranging from 0.656 to 0.806 for the informative style, 0.623 to 0.742 for the normative, 0.725 to 0.752 for diffuse-avoidant, and 0.635 to 0.776 for commitment. The correlation between the ISI-5 Indonesian version subscales in Table 2 shows that the informative style has positive correlation with the normative style (r = 0.505, p < 0.001) and commitment (r = 0.350, p < 0.001) and negatively correlated with the diffuse-avoidant style (r = -0.135, p < 0.001). The normative and diffuse-avoidant styles are positively related (r = 0.510, p < 0.001). On the contrary, the diffuse-avoidant style has a negative relationship with commitment (r = -0.576, p < 0.001). The ISI-5 Indonesian version scale has composite reliability of 0.757, 0.708, 0.787, and 0.821 for informative, normative, diffuse-avoidant styles, and commitment, respectively.  The correlation analysis in Table 3 shows a relationship between the ISI-5 Indonesian version subscale and other measuring instruments. The informative style has a positive relationship with almost all other measures. However, it has no relationship with the autonomy dimension of psychological well-being. Normative style is positively related to the three dimensions of identity and self-esteem and negatively related to the six dimensions of psychological well-being. The diffuse-avoidant style has a negative relationship with almost all other measures except self-esteem, in-depth exploration, and reconsideration of commitment, which are positively related. Commitment has a positive relationship with the majority of the other measures. However, it has no relationship with self-esteem and reconsideration of commitment.

Discussion
The confirmatory factor analysis results show that the identity style and commitment measurement model of the ISI-5 Indonesian version fits the data correctly. Furthermore, the reliability results showed that the ISI-5 has a composite reliability coefficient of more than 0.7 for the information, normative, and diffuse-avoidant subscales, with more than 0.8 for the commitment. A composite reliability coefficient greater than 0.7 is considered a satisfactory internal consistency estimate of the measurement model (Hair et al., 2014). This indicates that this version has good factor structure validity and reliability when tested on some Indonesian adolescents. These findings reinforce the factor structure's consistency, the three-factor identity styles' reliability, and the one-factor commitment models when examined in various countries (Crocetti et al., 2009;Crocetti & Shokri, 2010;Zimmermann et al., 2012).
The ISI-5 Indonesian version's correlation results are consistent with other measuring instruments in this research compared to previous studies. Therefore, the ISI-5 has fairly good criterion validity. Irrespective of the different correlation results from previous studies, it does not weaken the criterion validity of the ISI-5. This is because identity formation is contextual, thereby leading to the possibility of obtaining different results. Several studies have reported that it affects the differences in individuals' opportunities, expectations, and freedoms. Therefore, adapting to related contexts is an essential aspect of identity formation (Baumeister & Muraven, 1996;Bosma & Kunnen, 2001;Kroger, 2000;Phinney, 2005).
In general, the correlations of the identity style subscales are consistent with previous studies Berzonsky & Kuk, 2000;Berzonsky & Papini, 2015;Crocetti et al., 2013;. On the contrary, the correlation between the identity style sub-scales and commitment was unexpected. However, most previous studies stated that informative and normative styles have a positive relationship with commitment, while diffuse-avoidant is negatively related to commitment (Berzonsky, 2008;Berzonsky et al., 2013;. Different results were obtained from this research, with one stating that there was no relationship between normative style and commitment. However, this is consistent with previous studies, for example, a research carried out in Georgia (Skhirtladze et al., 2018) reported a negative relationship, while another conducted in Poland (Berzonsky & Cieciuch, 2016) found no relationship.
The results of the ISI-5 show that the normative style does not correlate with commitment. However, this is different from those obtained from U-MICS. Furthermore, the commitment from ISI-5 has a relatively strong correlation with the one from U-MICS. This is consistent with the results of previous studies (Crocetti et al., 2009;Muttaqin & Ekowarni, 2016;Zimmermann et al., 2012). It was also found that a relationship exists between the subscales of ISI-5 and U-MICS. However, it was discovered that normative style has a positive relationship with reconsideration of commitment.
The existence of a positive correlation between normative style and commitment from U-MICS as well as reconsideration of commitment shows that the adolescent's identity formation is unstable. Furthermore, individuals with normative styles tend to be committed. Conversely, the normative style used for identity formation causes adolescents to review their commitments. This is in accordance with its characteristics, such as internalizing commitment based on the significant expectations of others, for example, parents (Berzonsky, 2011;Berzonsky & Kuk, 2005;Berzonsky et al., 2013;. However, from an academic context, there is a possibility that adolescents rationally and analytically respond to the parents' expectations (Berzonsky, 2011;Crocetti et al., 2009;Crocetti et al., 2012). Therefore, it allows them to evaluate and reflect on previous parental expectations commitments (Crocetti et al., 2008).
Based on the correlation between identity style, commitment and self-esteem show that identity style was positively related to self-esteem, while no relationship was found between commitment and self-esteem. This contradicts previous (Crocetti et al., 2009;, which stated that there is a relationship between diffuse-avoidant styles, commitment, and self-esteem. The existence of a positive relationship between diffuse-avoidant styles and self-esteem indicates that certain motives cause individuals to develop identity formation . In an effort to maintain their self-esteem, they used diffuse-avoidant styles to develop identities according to situational demands. This is realized in order to maintain the individual's reputation and popularity in their social groups (Berzonsky, 1994;Berzonsky et al., 2003). Moreover, the Indonesian people are known as the collective society, which means that they pay more attention to the assessment of their social groups (Jandt, 2009). Therefore, it is possible that commitment is indeed not related to self-esteem, rather to collective self-esteem, which is more appropriate to society (Myers, 2013).
The relationship between informative, diffuse-avoidant, and commitment styles with psychological well-being dimensions is consistent with previous studies (Berzonsky & Cieciuch, 2016;Crocetti & Shokri, 2010;Vleioras & Bosma, 2005). However, the correlation between normative style and psychological well-being dimensions is inconsistent with previous studies, which tend to find a positive relationship. In contrast, this research discovered a negative relationship exists between normative styles and the six psychological well-being dimensions. Similar results were only found in a research carried out in Poland where normative style had a negative relationship with autonomy and personal growth (Berzonsky & Cieciuch, 2016). Specifically, the relationship between normative style and personal growth were discovered to have different correlation results in previous studies, for instance, it was positively related to adolescents in Iran (Crocetti & Shokri, 2010), negatively related to those in Poland (Crocetti & Shokri, 2010), and not related to adolescents in Greek (Vleioras & Bosma, 2005).
The negative correlation between normative style and psychological well-being dimensions is acceptable. This is due to the fact that the Indonesian community as a collective society has a hierarchical self-interdependence (Sartana & Helmi, 2014). This condition actually obliges adolescents in Indonesia to comply with their parents' expectations (Moffatt, 2012;Suardiman, 2011). On the other hand, the children's compliance is in order to satisfy their parents (Suardiman, 2011). When reviewing this condition, adolescents tend to ignore their personal desires in order to comply with parental expectations (Nilan et al., 2011). Therefore, their autonomy, environmental mastery, personal growth, positive relations with others, purpose in life, and selfacceptance tend to be limited. Moreover, individuals with a normative style automatically internalize and comply with the significant norms and expectations of others, such as parents, causing them to be dependent, become intolerant to uncertainty, and possess high self-control over traditional views (Berzonsky, 1989(Berzonsky, , 1990Berzonsky et al., 2013;Duriez et al., 2012;.

Conclusion
This research concluded that the ISI-5 Indonesian version is a valid and reliable measuring instrument. Therefore, it is used to measure the identity style in Indonesian adolescents. These instruments specifically measure three identity styles, namely: informative, normative, and diffuse-avoidant styles; and identity commitment.

Implication
As an effort to improve the measurement accuracy of the ISI-5 Indonesian version, further research needs to be carried out to test the convergent validity using constructs similar to identity styles such as identity status and cognitive reasoning.

Funding
There was no financial support in this research.

Author's contribution
Darmawan Muttaqin is responsible for overall article content by designing the study, preparing measurement tools, collecting data, analyzing data, and writing this article.

Conflict of interests
The author declares there is no conflict of interest in this research. The