by Uzma Ilyas, PhD scholar, and Prof. Dr. Saima Dawood, PhD 

Ms. Ilyas is with the Centre for Clinical Psychology, University of the Punjab. Prof. Dr. Dawood is Director, Centre for Clinical Psychology, University of the Punjab in Lahore, Pakistan. 

FUNDING: No funding was provided for this article.

DISCLOSURES: The authors have no conflicts of interest relevant to the content of this article.

Innov Clin Neurosci. 2024;21(4–6):19–24.

Abstract

The Social Interaction Anxiety Scale (SIAS) is a globally used scale for clinical diagnostic purposes for social anxiety disorder (SAD). This article investigates the psychometric properties of the SIAS, followed by its adaptation and validation in Urdu. The study consisted of two phases. The initial phase involved the translation of the scale, and the second phase was of a cross-sectional nature and consisted of evaluating factor structure and psychometric properties of the scale. For this purpose, the study enrolled a purposive sample of 573 adults aged between 18 to 45 years (mean [standard deviation (SD)] age: 23.68 [4.28] years) with a diagnosis of SAD. The sample was recruited from educational institutes, hospitals, and clinics in Lahore, Pakistan. The data was collected using a demographic form and the Urdu version of the SIAS, along with the Multidimensional Psychological Flexibility Inventory (MPFI). The analyses of the study were carried out using SPSS V27 and AMOS V24. Confirmatory factor analysis revealed a single factor structure of the Urdu version of the SIAS consisting of 16 items. The psychometric values of the scale shown were excellent, as Cronbach’s alpha equaled 0.91, convergent validity r equaled 0.37 at p less than 0.01 with psychological inflexibility, and discriminant validity r equaled –0.47 at p less than 0.01 with psychological flexibility. The study concluded that the Urdu version of the SIAS was a valid and reliable measure for the assessment of social anxiety in the Pakistani population.

Keywords: Confirmatory factor analysis, adaptation, validation, social anxiety disorder, psychometrics

Social anxiety disorder (SAD) is defined by a persistent fear of being judged by others, followed by the severe avoidance of social interactions and activities that might subject one to public scrutiny. The psychological discomfort is accompanied by physiological symptoms of sweating, heart palpitations, blushing, nausea, and restlessness.1 SAD is linked to excessive shyness, absence from school, mutism, and behavioral inhibition, which can severely impair social, intellectual, and professional functioning.2 Studies suggest that SAD most commonly originates during adolescence (prior to the age of 18 years)3 and up to nine percent of teenagers are diagnosed with SAD in the United States (US).4 In addition to age, data have shown that more women are diagnosed with SAD, compared to men.5

According to research conducted in various parts of the world, SAD as a notable prevalence among various population groups. About 7.8 percent of Indian undergraduate students,6 36 percent (mild SAD) and 12 percent (severe SAD) of Malaysian students,7 and about 46 percent of Omani adults have SAD.8 A recent study that estimated the prevalence of social anxiety across seven economically diverse countries reported that one out of three individuals scored above threshold of SAD (36%).9 Prevalence rates among Pakistani students were found to be about 23 percent,2 which raises the concerns of clinicians and researchers, who might request early screenings of social anxiety to avoid its repercussions. Despite having a significantly high prevalence of SAD, the majority of the scales used in Pakistan for the assessment and diagnosis of SAD are in the English language.10 This existing language barrier might lead to inaccurate conclusions related to SAD or social anxiety. Moreover, people in diverse civilizations typically interpret situations differently and respond to them in accordance with their own cultural perspectives due to the fact that different cultures have distinct social norms, environments, and social demands. Therefore, owing to these cultural restrictions, it is imperative to employ the scales in a local language that would be more comprehensible for the Pakistani clinical population with a basic understanding of Urdu. To this end, the Anxiety Scale for Adults (ASA) was recently developed in Pakistan to assess anxiety levels; this scale is relatively longer and was based on a smaller number of participants from a single city.11 Despite being a step forward for the assessment of anxiety, it is not a handy assessment in this culture, where psychological assessment is unconventional and people tend to avoid lengthy diagnostic procedures. 

As far as established measures of social anxiety are concerned, there are a few that have earned a worldwide reputation, including the Liebowitz Social Anxiety Scale (LSAS),12 Social Phobia Scale (SPS),13 Social Interaction Anxiety Scale (SIAS),13 and Social Anxiety Scale (SAS-A).14 In Pakistan, studies have also been conducted to validate the measures of social anxiety among a nonclinical population. For instance, the SAS-A and the SIAS have been validated in the Urdu language on the student population.15,16 However, empirical evidence suggests an absence of validation studies of these established measures among clinical patients with SAD. This lack of availability of valid and reliable adaptive measures for the clinical population hinders the screening of SAD in Pakistan. 

Among these well-established scales for social anxiety, the SIAS is well-recognized. It is a 20-item self-report scale that assesses a person’s overall reluctance toward social interaction, such as starting and maintaining conversations. The scale, developed by Mattick and Clarke,13 was based on the conceptualization that social anxiety is experienced in two types of situations involving social interaction and scrutiny by others. This notion and the need for an instrument resulted in development of the SIAS and SPS. The SIAS calibrated commonly feared social situations, and the SPS was developed to measure anxiety related to social performance.13 The full version of SIAS has 20 items; however, there is also a version available that comprises 19 items (excluding Item 5).17 Validation of the SIAS into different languages has shown excellent psychometric standing in measuring manifestations of symptomatology of social anxiety in terms of interaction and evaluation by others.17,18 

The SIAS is regarded as a brief reflective tool and has been cited in research more than 4,000 times. It is used broadly for two situations: to assess social anxiety and evaluate the outcome of psychotherapeutic intervention.19 It also appeared to discriminate between individuals without social anxiety and those with clinical social anxiety.20 Moreover, it presents a sound psychometric standing, as it has shown good reliability21,22 and satisfactory validity scores21 for its full length and short form.23 Due to its psychometric properties and comprehensive covering of social anxiety as well as social phobia, the SIAS has already been adapted into Farsi,24 Chinese,23 Indian,6 Japanese,25 and Dutch.21 Based on the above-mentioned literature, it is clear that the SIAS is a brief and well-established tool. The recent validation of the SIAS among the student population in Pakistan,16 although limited in scope, is not only a step toward using valid and reliable measures that are accepted across world in Pakistan, but also points the clinical reputation of the SIAS as a valuable assessment of SAD. 

The SIAS has been validated across populations in different languages, but no recent study has reported its validation in Urdu with clinical patients.16–18 Considering the clinical significance of SAD and the culture-dependent nature of its prevalence and manifestation,9 validation of the SIAS could be considered indispensable for its clinical use. Therefore, the current study aimed to translate and adapt the SIAS into Urdu and evaluate the factor structure for the adapted Urdu version of the SIAS by sampling clinical patients with SAD.

Materials and Methods

The first phase consisted of translation and adaptation of the SIAS, and the second phase consisted of its factor structure and psychometric evaluation. The study was carried out from October 2021 to December 2022. It followed important ethical considerations, including written informed consent, debriefing, right to withdraw, and confidentiality.  The study recruited participants with mild-to-moderate scores on the SIAS, while individuals with severe anxiety (identified during screening) were referred to Trauma Centre, Centre for Clinical Psychology, University of the Punjab, for psychological help. 

Phase 1. In the first phase of study, the cultural relevance of the scale was sorted, and the 20-item version of the SIAS was translated into Urdu following the guidelines provided by the International Test Commission (ITC) after obtaining permission from the authors of the scale. Initially, the scale was forward translated into the Urdu language by three bilingual experts from the field of clinical psychology. The initial translations were then subjected to modifications by researchers and experts to reach a conclusion with consensus based on its face validity and cultural context. During this process of adaptation, the Urdu translation of two items in the SIAS (Items 14 and 20) was modified. Item 14 was modified to make it more culturally acceptable to assess anxiety in the context of talking with the opposite sex, as in Pakistani culture, people are already cautious while talking with the opposite sex. In addition, Item 20 was adapted in the context of the initiation of social interaction, with people hardly having any acquaintance instead of greeting; in the Pakistani context, people say greetings even to those with whom they have no-to-slight acquaintance. It was noted by the researcher that in collectivistic culture, people often even greet strangers, as it is a norm. This consolidated version, obtained after forward translation, was further subjected to back-translation into English by another group of independent bilingual experts, and a final version was obtained after reviewing the existing translations. This final adapted version of the scale, consisting of 20 items, was pilot tested with 30 subjects (clinical and nonclinical, 15 subjects each), which provided a satisfactory response to undertake the next phase.

Phase 2. The second phase consisted of validation of the scale. The Urdu translation of the SIAS was subjected to confirmatory factor analysis to assess its factor structure. To conduct confirmatory factor analysis by considering Kline’s guidelines,26 data from a minimum of 200 participants is required, whereas the participants per variable ratio suggest data from 100 participants. However, the published literature suggests using data from 300 participants or greater. Participants were recruited from public and private hospitals, student counseling centers at educational institutes, and private clinics in Lahore. The clinical psychologists working at these data sites were requested to refer those patients who fulfilled the inclusion criteria of SAD, as per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and were receiving counseling or medications for SAD for recruitment to the study. Participants aged 18 years or older and having the ability to comprehend Urdu were considered eligible. Participants who were unable to give consent, had any other comorbid psychiatric disorders, or had any physical disability were excluded from the study. After discarding ineligible cases and sorting missing data, a final sample of 573 participants was selected for the present study.

A set of questionnaires were administered to participants to collect data. The demographic form was used to obtain the demographic information of participants, such as age, sex, marital status, education, family backgrounds, any comorbid physical and psychological illnesses (for the purpose of exclusion), history of illness, and treatment duration (if any sorted). Along with the demographic form, the Urdu translation of the SIAS was administered to the participants. The SIAS is a self-report scale that measures anxiety or distress that individuals face during social interaction.13 Its items are rated on a five-point Likert scale that is marked from 0 (“Not at all a characteristic or true of me”) to 4 (“Extremely characteristic or true of me”). The three items of scale are positively worded and reverse scored to obtain the total scale score, which can range from 0 to 80. Lastly, the Urdu translation of the Multidimensional Psychological Flexibility Inventory (MPFI), developed by Rolffs et al,27 was utilized. It consists of 60 items that are classified into two factors: psychological flexibility and psychological inflexibility. The items are rated on a seven-point Likert scale, ranging from 1 (“Never true”) to 6 (“Always true”), and a high score on a particular dimension indicates a higher aspect of that dimension. The total score of psychological flexibility and psychological inflexibility is the sum of item scores on each factor. In the current study, both of the factors of scale of the MPFI were used to assess both convergent and discriminant validity. 

For the present study, statistical analyses were carried out using SPSS V27 and AMOS V24. Descriptive statistics were calculated for demographic data. To access the factor structure to be replicated on the new data, a confirmatory factor analysis was carried out. The model-fit criteria, including the relative Chi-squared index (CMIN/DF), goodness-of-fit index (GFI), Tucker-Lewis index (TLI), comparative-fit index (CFI), root mean square error of approximation (RMSEA), and standardized root mean square residual (SRMR), were used to examine the goodness-of-fit of the model on the given dataset. After the model evaluation process, the construct reliability was established using Cronbach’s alpha reliability of items consisting of the scale. For convergent validity and discriminant validity, correlation analysis was used. 

Results

Among the study participants, 51 percent (n=294) were male and 49 percent (n=278) were female. Participants were aged between 18 to 45 years. The mean age of the study participants was 23.68 years, and a large proportion (46%) had a MPhil degree. Most participants were unmarried and had middle class socioeconomic background. The characteristics of study participants are given in Table 1.

 The confirmatory factor analysis performed on the sample data obtained for the original 20 items of SIAS reflected a poor fit (Table 2). The initial model, consisting of four items, had factor loadings below 0.4. To improve the model, the data output and factor loadings were thoroughly analyzed. Following this, four items (4, 5, 9, and 10) with poor factor loadings (<0.4)28 were removed from the model one by one. Two of these items are reversely coded, and studies have also suggested not including them in the SIAS, as they appear to be related with extraversion.29,30 Thus, these items, along with other items, were removed based on their loading and provisions from the literature. 

 In addition, the model was also modified by merging error covariances, while also calculating the model fit estimates for each modification in the model. This resulted in improved model-fit values. The model showing an absolute fit as Chi-squared/degree of freedom (df) less than five, RMSEA less than 0.08, and SRMR less than 0.0831 were regarded as final. Furthermore, the incremental fit assumptions, such as GFI, CFI, and TLI,32 were also fulfilled for the final model. The items loadings of the final model (Table 3) were greater than 0.40 and fulfilled criteria given by Stevens,28 except for one item that had a loading of 0.39; however, it was still acceptable.33 This item was retained, despite its poor loading, to preserve the content validity of the construct. The final model consisted of a single factor with 16 items. Overall, the final model showed a satisfactory fit and met the required criteria of goodness-of-fit indices.

The reliability analysis was carried out on 16 items of the final Urdu version of the SIAS, and it showed Cronbach’s alpha reliability value of  0.91. The correlation used the sum of the total items score for each scale to calculate mean and standard deviation (Table 4). The convergent validity assessed through the correlation of the SIAS with the psychological inflexibility scale of the MPFI was found to be significantly positive (p<0.01). The SIAS established discriminant validity through a significant inverse relationship with the psychological flexibility scale of the MPFI (p<0.01). Moreover, age showed a significant positive association with the flexibility scale, and no significant observation was made for the SIAS and psychological inflexibility scores. 

Discussion

The SIAS has immense importance in the assessment of SAD due to its clinical sensitivity. It is of the utmost significance that clinical and psychiatric screenings calibrate the detrimental effects of social anxiety. The current study also attempted to evaluate the factorial structure and psychometric properties of an Urdu version of the SIAS. The confirmatory factor analysis performed in the current study showed a one-factor structure of the scale with 16 items. The psychometric analysis of the Urdu version of the scale was demonstrated to be a valid and reliable measure of social anxiety. 

Previous studies have reported varied factor structures of the SIAS and its adapted versions; single-factor solutions21 and two- or three-factor structures20,34 have been reported. In a recent study in Pakistan,16 the SIAS showed a four-factor structure with a nonclinical sample that contradicts the ones reported in literature. These differing factor structures indicate the need to validate this scale for the screening of social anxiety in the clinical population of Pakistan. The single-factor structure of the SIAS in the present study is in line with previous literature that reports a single-factor solution of the scale as appropriate.21 Differing from current findings, existing research also reports a bifactor model using both the SIAS and SPS (a general factor covering both aspects of social anxiety) and suggests social anxiety as a dimensional, rather than categorical, construct.17,35 

During the translation process, items were carefully evaluated based on cultural relevance and indicated commonly reported symptoms of social anxiety among patients. The content of these items encompasses the themes of public embarrassment, physiological symptoms of nervousness, and difficulty interacting and communicating with people. Such themes are well recognized and observable in collectivistic culture in the form of shy and introverted behavior. The existing literature also corroborates these findings, showing that cultural norms set the stage for social anxiety. In collectivist cultures, people are more likely to behave in a socially anxious and avoidant manner that, at times, is confused with etiquette. Such behaviors are considered acceptable and receive positive attitudes in social and interpersonal contexts. The responses of the participants on the measure of social interaction anxiety show that adolescents from Asian cultures are at higher risk of social anxiety disorders, compared to those living in individualistic cultures.36 However, it is also suggested that social concerns be evaluated in the context of a person’s background to understand the extent and expression of social anxiety.37 The current study has also established the content and face validity of the scale during scale translation based on expert opinions.

The Urdu version of the SIAS appeared to be valid and reliable because it showed satisfactory psychometric properties. The scale provided an internal consistency value of 0.91, which was good.38 The scale also showed a significant correlation with the psychological flexibility and inflexibility subscales of the MPFI, establishing its discriminant and convergent validity, respectively. Overall, the correlations remained moderate,39 and the single-factor Urdu version of the SIAS appeared to have a satisfactory psychometric standing. 

In the current study, one factor was retained and four items were removed. The SIAS was developed based on the definition of social anxiety in the DSM-III, and the DSM has evolved since then; therefore, that representation of the disorder might not be accurate. One important factor that needs to be mentioned is that data was collected from individuals who reported mild-to-moderate anxiety on the SIAS; if individuals with a greater severity of social anxiety as per the SIAS had been added to the sample, then some items might have been retained. Due to ethical considerations, a bigger pool of individuals with severe anxiety was not recruited as protocol and assessment measures were in the process of modification. Since the current study shows a satisfactory reliability of the SIAS, it can be assumed that that the retained items can screen and measure social anxiety in Pakistani culture, irrespective of its structures reported in validation studies of versions adapted into other languages.16,20,21 Moreover, the single-factor structure of the SIAS recommends the assessment of social anxiety on a continuum and suggests it as a continuous dimension. It provides empirical evidence to use the SIAS in the screening of clinically significant social anxiety in SAD. 

Translation and adaptation of a scale into different cultures can yield contrasting results. During translation, some words or phrases in the original language lose their essences and meanings when translated into another language.40 Therefore, the different language can also be another factor in the current results. The current adapted scale will be beneficial to use in cultures and places where Urdu is spoken, and it is also a quick and reliable screening tool. Culture plays a very important role in the trajectory of disorders, and there is a need to develop a cultural model for anxiety so that it can be better understood in the course of treatment, as well as its prevalence and chronicity.41

Strengths and limitations. The current study has its strengths, as the SIAS was validated on a large clinical sample with the evaluation of its factor structure. This study is also an important contribution to the existing literature in terms of the clinical usefulness of the Urdu version of the SIAS for the screening of social anxiety among the clinical and nonclinical populations. The Urdu version appears to be particularly useful for Pakistani people with diverse cultural backgrounds and are not proficient in the English language. Moreover, it can also facilitate the communication of symptoms in clinical settings around the world, as there might be occasions when individuals from Asian backgrounds, such as refugees, migrants, and those who only speak or understand Urdu and Hindi, are required to be accommodated clinically. Apart from diagnostic assessments, the Urdu version of the SIAS will be useful in interventional assessments as well. Overall, this study promotes the use of a more comprehensive and brief measure of social anxiety, which not only captures SAD but also social phobia. 

The study had several limitations. It sampled a only single metropolitan area and could not capture SAD among people native to other parts of Pakistan and those who do not understand Urdu well. Future studies should focus on examining use of the scale in diverse groups.

Conclusion 

The Urdu version of the SIAS is a valid and reliable measure for the assessment of social anxiety in Pakistan. The Urdu version of the scale is a psychometrically sound measure and can be used for the clinical and research purposes in the Pakistani cultural context.

Acknowledgement

We would like to acknowledge Trauma Centre, Centre for Clinical Psychology at University of the Punjab for providing the facility to the researcher to facilitate referral of participants who intend to seek psychological services.

References

  1. National Institute of Mental Health. Social anxiety disorder: more than just shyness. Revised 2022. https://www.nimh.nih.gov/health/publications/social-anxiety-disorder-more-than-just-shyness. Accessed 25 Mar 2023.
  2. Bano Z, Riaz A, Riaz S. Social anxiety in adolescents: prevalance and morbidity. Pak Armed Forces Med J. 2019;69(5):1057–1060.
  3. Stein DJ, Lim CC, Roest AM, et al. The cross-national epidemiology of social anxiety disorder: data from the World Mental Health Survey Initiative. BMC Med. 2017;15(1):143. 
  4. Alves F, Figueiredo DV, Vagos P. The prevalence of adolescent social fears and social anxiety disorder in school contexts. Int J Environ Res Public Health. 2022;19(19):12458. 
  5. Asher M, Asnaani A, Aderka IM. Gender differences in social anxiety disorder: a review. Clin Psychol Rev. 2017;56:1–12.
  6. Honnekeri BS, Goel A, Umate M, et al. Social anxiety and Internet socialization in Indian undergraduate students: an exploratory study. Asian J Psychiatr. 2017;27:115–120. 
  7. Isa R, Mohd Norsabri NA, Mohd Zamri NA. Social anxiety and the quality of life among undergraduate students in UiTM Puncak Alam Campus. Healthscope. 2021;4(1):13–19. 
  8. Ambusaidi A, Al-Huseini S, Alshaqsi H, et al. The prevalence and sociodemographic correlates of social anxiety disorder: a focused national survey. Chronic Stress (Thousand Oaks). 2022;6:24705470221081215.
  9. Jefferies P, Ungar M. Social anxiety in young people: a prevalence study in seven countries. PLoS One. 2020;15(9):e0239133. 
  10. Ejaz B, Muazzam A, Anjum A, et al. Measuring the scale and scope of social anxiety among students in Pakistani higher education institutions: an alternative social anxiety scale. Sustainability. 2020;12(6):2164.
  11. Bano Z, Ejaz M, Ahmad I. Assessment of prevalence of anxiety in adult population and development of anxiety scale: a study of 819 patients with anxiety disorder. Pak J Med Sci. 2021;37(2):472–476.
  12. Liebowitz MR. Social phobia. Mod Probl Pharmacopsychiatry. 1987;22:141–173. 
  13. Mattick RP, Clarke JC. Development and validation of measures of social phobia scrutiny fear and social interaction anxiety. Behav Res Ther. 1998;36(4):455–470. 
  14. La Greca AM, Lopez N. Social anxiety among adolescents: linkages with peer relations and friendships. J Abnorm Child Psychol. 1998;26(2):83–94.
  15. Ahmad R, Bano Z. Translation and psychometric assessment of Social Anxiety Scale for Adolescents in Pakistan. Pak J Psychol. 2013;44(1):67–80.
  16. Ahmed I, Ahmed I, Khan F, Iet al. Psychometric testing of Social Interaction Anxiety Scale in Pakistani context. Elementary Education Online. 2021;20(5):707–719.
  17. Gomez R, Watson SD. Confirmatory factor analysis of the combined Social Phobia Scale and Social Interaction Anxiety Scale: support for a bifactor model. Front Psychol. 2017;8:70. 
  18. Eidecker J, Glöckner-Rist A, Gerlach AL. Dimensional structure of the Social Interaction Anxiety Scale according to the analysis of data obtained with a German version. J Anxiety Disord. 2010;24(6):596–605. 
  19. Acarturk C, Cuijpers P, van Straten A, de Graaf R. Psychological treatment of social anxiety disorder: a meta-analysis. Psychol Med. 2009;39(2):241–254. 
  20. Mörtberg E, Reuterskiöld L, Tillfors M, et al. Factor solutions of the Social Phobia Scale (SPS) and the Social Interaction Anxiety Scale (SIAS) in a Swedish population. Cogn Behav Ther. 2017;46(4):300–314.
  21. de Beurs E, Tielen D, Wollmann L. The Dutch Social Interaction Anxiety Scale and the Social Phobia Scale: reliability, validity, and clinical utility. Psychiatry J. 2014;2014:360193. 
  22. Ye D, Qian M, Liu X, Chen X. Revision of Social Interaction Anxiety Scale and Social Phobia Scale. Chinese J Clin Psychol. 2007;15:115–117.
  23. Ouyang X, Cai Y, Tu D. Psychometric properties of the short forms of the Social Interaction Anxiety Scale and the Social Phobia Scale in a Chinese college sample. Front Psychol. 2020;11:2214.
  24. Tavoli A, Allahyari A, Azadfallah P, et al. Validity and reliability of the Farsi version of Social Interaction Anxiety Scale (SIAS). Iran J Psychiatr Clin Psychol. 2012;18(3):227–232.
  25. Maeda S, Shimada H, Sato T, et al. Translation and initial validation of the Japanese Version of the Self-Beliefs Related to Social Anxiety Scale. Psychol Rep. 2017;120(2):305–318. 
  26. Kline RB. Principles and Practice of Structural Equation Modeling, Fourth Edition. New York, NY: The Guilford Press; 2016.
  27. Rolffs JL, Rogge RD, Wilson KG. Disentangling components of flexibility via the Hexaflex Model: development and validation of the Multidimensional Psychological Flexibility Inventory (MPFI). Assessment. 2018;25(4):458–482.
  28. Stevens J. Applied Multivariate Statistics for the Social Sciences, Second Edition. Mahwah, NJ: Lawrence Erlbaum Associates; 1992.
  29. Le Blanc AL, Bruce LC, Heimberg RG, et al. Evaluation of the psychometric properties
  30. of two short forms of the Social Interaction Anxiety Scale and the Social Phobia Scale. Assessment. 2014;21(3):312–323.
  31. Rodebaugh TL, Woods CM, Heimberg RG. The reverse of social anxiety is not always the opposite: the reverse-scored items of the Social Interaction Anxiety Scale do not belong. Behav Ther. 2007; 38(2):192–206. 
  32. Garson GD. Partial Least Squares: Regression and Structural Equation Models. Asheboro, NC: Statistical Associates Publishing; 2016.
  33. Hair JF, Black WC, Babin BJ, et al. Multivariate Data Analysis, Seventh Edition. Pearson; 2010.
  34. Comrey AL, Lee HB. Interpretation and application of factor analytic results. In: AL Comrey AL, Lee HB (eds). A First Course in Factor Analysis, Second Edition. Hillsdale, NJ: Lawrence Eribaum Associates; 1992.
  35. Zsido AN, Varadi-Borbas B, Arato N. Psychometric properties of the Social Interaction Anxiety Scale and the Social Phobia Scale in Hungarian adults and adolescents. BMC Psychiatry. 2021;21(1):171. 
  36. Šipka D, Brodbeck J, Schulz A, et al. Factor structure of the Social Phobia Scale (SPS) and the Social Interaction Anxiety Scale (SIAS) in a clinical sample recruited from the community. BMC Psychiatry. 2023;23(1):646.
  37. Krieg A, Xu Y. From self-construal to threat appraisal: understanding cultural differences in social anxiety between Asian Americans and European Americans. Cultur Divers Ethnic Minor Psychol. 2018;24(4):477–488.
  38. Washburn D, Wilson G, Roes M, et al. Theory of mind in social anxiety disorder, depression, and comorbid conditions. J Anxiety Disord. 2016;37:71–77. 
  39. De Vellis RF. Scale Development: Theory and Applications, Second Edition. Thousand Oaks, CA: Sage Publications; 2003.
  40. Ratner B. The correlation coefficient: its values range between +1/−1, or do they? J Target Meas Anal Mark. 2009;17(2):139–142.
  41. Qadir F, Maqsood A, Us-Sahar N, et al. Factor structure of the Urdu version of the Spence Children’s Anxiety Scale in Pakistan. Behav Med. 2018;44(2):100–107.
  42. Hinton DE, Lewis-Fernandez R. Idioms of distress (culturally salient indicators of distress) and anxiety disorders. In: Simpson HB, Neria Y, Lewis-Fernandez R, Schneier F, (eds). Anxiety Disorders: Theory, Research, and Clinical Perspectives. Cambridge University Press; 2010:127–138.