A MALAY VERSION OF PERCEIVED STRESS SCREENING SCALE (PSS-10): PSYCHOMETRIC EVALUATION AMONG MANUFACTURING INDUSTRY WORKERS

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1 ORIGINAL ARTICLE A MALAY VERSION OF PERCEIVED STRESS SCREENING SCALE (PSS-10): PSYCHOMETRIC EVALUATION AMONG MANUFACTURING INDUSTRY WORKERS Lim Chee Siang. 1, Mohd Rafee Baharuddin. 1*, Anita Abd Rahman. 1, Shamsul Azhar Shah. 2, Samsul Bahari Mohd Noor. 3 1 Department of Community Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia. 2 Department of Community Health, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latif, Bandar Tun Razak, Cheras, Kuala Lumpur, Malaysia. 3 Department of Electrical and Electronic Engineering, Faculty of Engineering, University Putra Malaysia, UPM Serdang, Selangor, Malaysia. ABSTRACT The 10-item Perceived Stress Scale (PSS-10) is one of the most widely used scales for measuring psychological stress. It has been translated into more than 25 languages and validated among different populations. This study evaluated psychometric properties of Malay version PSS-10 in measuring perceived stress among manufacturing industry workers. A cross-sectional study was conducted in random sample of 42 workers from a pipeline manufacturing company. The Malay version PSS-10 was translated and back translated from original PSS-10. Psychometric properties of PSS-10 were evaluated by principal component analysis (construct validity), Cronbach`s alpha coefficients (internal consistency) and correlation coefficients with the 21-item Depression, Anxiety, and Stress Scale (DASS-21) (concurrent validity). There were no significant differences of PSS-10 scores (M=17.4) across socio-economic characteristics (p>.05). Principal component analysis with varimax rotation showed a 2-factors structure that accounted for 48.59% of the variance (Factor loadings: ). The Kaiser-Meyer-Olkin value (0.66) and significant Bartlett`s Test of Sphericity suggested that the items were appropriate and adequate for factor analysis. Acceptable internal consistency was observed (α=0.77). Concurrent validity of PSS-10 was reflected as the moderate correlations with DASS-21 stress subscale [r(40)=0.58, p<.05]. Severely stressed respondents as classified according to DASS-21 scores had significantly higher PSS-10 scores compared to normal respondents. [F(3,38)=4.21, p<.05]. This is the first study in Malaysia to evaluate the psychometric properties of PSS-10 among manufacturing industry workers. The findings supported that Malay version PSS-10 is a valid and reliable scale to measure perceived stress level of the population. Keywords: PSS, perceived stress, psychometric property, manufacturing industry, validity, reliability. INTRODUCTION Stress is a universal phenomenon that has long been studied by many prominent researchers with divergent opinions and perspectives about it. World Health Organization defines stress as the reaction people may have when presented with demands and pressures that are not matched to their knowledge and abilities and which challenge their ability to cope. Stress occurs when an individual perceives that environmental demands exceed his or her adaptive capacity 1. Research findings even show that stress were linked with numerous emotional and physical disorders including depression, anxiety, heart attacks, stroke, hypertension and diabetes 2-4. It is one of the most common psychosocial hazard at workplace 5. Therefore, it is important for an individual to monitor and manage stress to maintain physical and mental well-being. A lot of scales that could measure stress level were developed and validated in different populations by researchers. For example, the Depression, Anxiety and Stress Scale (DASS) 6, the Perceived Stress Scale (PSS) 7, the Stress Appraisal Measure 8 and the Trier Inventory of Chronic Stress 9. Among these, PSS is one of the most widely used scales for measuring psychological stress. PSS is a self-reported questionnaire that was designed to measure the degree to which individuals appraise situations in their lives as stressful. The original PSS was a 14-item scale that contain 7 negative items and 7 positive items. Subsequently, 4 items with relatively low factor loading were deleted from PSS-14 and a shortened version of PSS (PSS-10) with only 10 items was introduced by the author 10. In this study, PSS-10 was used because it has better psychometric properties and shorter administration time as compared to PSS-14. PSS-10 has been translated and validated in more than 25 languages other than English including Spanish, Danish, Japanese, German, and Thai 11. In Malaysia, both Malay and English version of PSS-10 has been used in clinical and non-clinical studies. The Malay version of PSS-10 has shown good psychometric properties over specific Malaysian population such as medical students, diabetic patients, railway workers and prisoners but not among manufacturing industry workers Malaysia is a middle-income going to high-income country that relies heavily on trade, especially on the products of manufacturing industry. Manufacturing industry had contributed about 28%

2 of Malaysia Gross Domestic Product and 16.8% of total Malaysia workforce in Given that perceived stress has been closely related with organization such as absenteeism, turnover, time performance, productivity, morale and accidents 17, 18, it is essential to have a measure of perceived stress validated in Malaysia manufacturing industry worker. This study is the first in Malaysia, to our knowledge, that evaluates the psychometric properties of PSS-10 among manufacturing industry workers. METHODOLOGY Study design and study population A cross-sectional study was conducted among workers of a pipeline manufacturing company at Kuantan, the capital of Pahang state in mid- November This study was a pilot study of larger study conducted by the authors which examined the effectiveness of participatory ergonomics intervention in reducing stress level among manufacturing industry worker. The sample size of this study was 42, which was 9% of the sample size projected for larger parent study, as suggested by Cocks and Torgerson 19. A written permission and name list of workers who are above 18 years old and have been working for the company for at least 3 months was obtained from the Human Resource Department of the company. The workers were then selected through simple random sampling, where they were assigned with random numbers using Microsoft Excel Software and the first 42 workers in the list were recruited as the study respondents. Written informed consent from all the respondents were obtained before administering the questionnaires. The research protocol was approved by the Research Ethics Committee of Universiti Putra Malaysia (UPM). Measures Perceived Stress Scale (PSS-10) PSS-10 is a 10-items scale, which comprised of 6 negatively stated items (item 1, 2, 3, 6, 9 and 10) that measure individual perceived stress and 4 positively stated items (item 4, 5, 7 and 8) that measure individual coping ability. Respondents rated the occurrence frequency of each item during the last month based on a 5-point Likert scale that ranged from 0 (never) to 4 (very often). PSS-10 scores are obtained by summing across all items after reversing the scores of the 4 positively stated items. Total scores of PSS-10 ranged from 0 to 40 and higher scores indicates greater individual perceived stress. PSS-10 was forward translated from the original English version to Malay version by the author and another postgraduate student who possess strong command of English and Malay languages. Translation process aimed at the conceptual equivalent of a word or phrase rather than literal translations. The translated scale was then reviewed by a senior lecturer in Public Health at the Department of Community Health, UPM to identify and resolve inadequate expressions of the translation. The translated and reviewed version was then back translated from Malay version to English version by another postgraduate student who has no knowledge on the original scale to identify problematic words or phrases aroused during translation process and to ensure face validity of the scale. Both scales were compared and discrepancies were discussed to produce a satisfactory version of scale. The final version of PSS-10 was pre-tested among 5 postgraduate students prior to actual data collection. Depression, Anxiety and Stress Scale (DASS-21) The DASS-21 is a self-reported questionnaire that was designed to measure the negative emotional states of depression, anxiety and stress 6. It has been translated into many languages such as Chinese, Portuguese, Nepali, and so on DASS- 21 consisted of 3 subscales (DASS-Depression, DASS-Anxiety and DASS-Stress) and each subscale contains 7 items. Respondents rated the extent to which they have experienced each state in the item over the past week based on a 4-point Likert scale that ranged from 0 (Did not apply to me at all) to 3 (Applied to me very much, or most of the time). DASS-21 scores for each subscale are obtained by summing across all items in the subscales. Final score of each subscale is then multiplied by 2 and compared with DASS profile sheet to know the degree of severity. The severity of stress is classified as normal level (<14), mild level (15-18), moderate level (19-25), severe level (26-33) or extremely severe level (>34) based on respondent`s final score. DASS-21 was previously used as the gold standard to estimate concurrent validity of PSS-10 as both scales measure similar constructs 23, 24. In this study, validated Malay version of DASS-21 was used as it has shown good psychometric properties among manufacturing industry worker 25, 26. Statistical analysis Data entry and analysis were performed using the Statistical Package for the Social Sciences (SPSS) version Before further statistical analysis was conducted, data was screened for accuracy, missing values, outliers and normality. PSS-10 scores and DASS-21 scores were normally distributed as shown by Shapiro-Wilk test (p >.05). For descriptive analysis, categorical data was presented in frequency and percentage while continuous data was presented in mean (M) and standard deviation (SD). Independent-Samples T Tests or one-way ANOVA tests as appropriate were conducted to determine differences in PSS scores across socio-demographic characteristics. For construct validity of PSS-10, principal component analysis was conducted to extract the factors using varimax rotation (eigenvalues > 1). Factor loading values > 0.40 were considered as indicators of significant factorial contribution 27. Sample adequacy and appropriateness were

3 further assessed by the Kaiser-Meyer-Olkin (KMO) measure and Barlett s Test of Sphericity. Cronbach`s alpha coefficients were computed to determine the internal consistency of PSS-10. Alpha (α) value > 0.7 was considered acceptable 28. Concurrent validity of PSS-10 was evaluated using Pearson correlation test with 3 subscales of DASS- 21. The differences of PSS scores were compared among different severity of stress according to DASS scores using one-way ANOVA test. All the statistical analysis results were considered significant at p <.05. RESULTS Socio-demographic characteristics and PSS-10 scores of respondents Table 1 illustrates the socio-demographic characteristics and mean PSS scores of the 42 male workers who joined the study. The mean (SD) age of the respondents was 24.9 (5.3) years. Majority of the respondents were singles (73.8%), attained secondary school levels (88.1%) and worked as operators or general workers (88.1%). There were 81% of the respondents reported of working more than 48 hours weekly inclusive of overtime, which have exceeded the maximum standard working time as recommended by International labour Organization (ILO). Despite having extended working hours, 54.7% of respondents were reported of having monthly income less than RM A total of 31 respondents are current smoker and 26 of them spend at least 1 to 3 hours weekly for sport activities or exercises. The mean (SD) PSS score of the respondents was 17.4 (3.3). Independentsamples t-tests and one-way ANOVA tests revealed that there were no significant differences in PSS scores across sociodemographic characteristics such as marital status, education attainment, work position, monthly income, work duration, smoking status and duration of exercise (p >.05). Table 1. Socio-demographic Characteristics and PSS-10 Scores of Respondents (N = 42) Variables Mean (SD) Frequency (%) Mean PSS score (SD) p Age (years) 24.9 (5.3) 17.4 (3.3) - Gender Male 42 (100) 17.4 (3.3) - Marital status Single 31 (73.8) 17.4 (3.1) 0.99 b Married 10 (23.8) 17.4 (4.2) Divorced 1 (2.4) 18.0 (0.0) Educational attainment Secondary School 37 (88.1) 17.3 (3.4) 0.59 a Diploma 5 (11.9) 18.2 (3.6) Work position Operator/General worker 37 (88.1) 17.4 (3.4) 0.69 a Supervisor 5 (11.9) 18.0 (2.9) Monthly income (RM) (54.7) 17.8 (3.1) 0.46 b (40.5) 16.7 (3.8) > (4.8) 19.0 (1.4) Work duration (hours) (9.5) 16.5 (2.1) 0.84 b (9.5) 17.3 (5.4) > (81.0) 17.6 (3.3) Smoking status Never smoker 6 (14.3) 16.5 (3.0) 0.74 b Former smoker 5 (11.9) 18.0 (2.6) Current smoker 31 (73.8) 17.5 (3.5) Duration of exercise weekly Never 13 (31.0) 17.8 (2.0) 0.78 b 1 3 hours 26 (61.9) 17.2 (3.9) > 3 hours 3 (7.1) 18.3 (3.2) a Independent-samples t-test; b one-way ANOVA test Construct validity The Kaiser-Meyer-Olkin value of the study was 0.66 (> 0.5), indicating sampling adequacy while the Bartlett`s Test of Sphericity was significant (p <.05), suggesting that the items were appropriate for factor analysis. As shown in Table 2, the principal component analysis with varimax rotation of all the 10 items in PSS, yielded the extraction of two factors that could explained 48.6% of the variance. Factor 1 consisted of 6 items (1, 2, 3, 6, 9 and 10) that were related with perceived stress and had accounted for 34.4% of the variance. The factor loading of items ranged from 0.56 to Factor 2 consisted of 4 items

4 (4, 5, 7 and 8) that were related with coping ability and had accounted for 14.2% of the variance. The factor loading of items ranged from 0.45 to Table 2. Items and Factor Loading for PSS-10 using Principal Component Extraction and Varimax Rotation Items Factor 1 (α = 0.79) 1. In the last month, how often have you been upset because of something that happened unexpectedly? In the last month, how often have you felt unable to control the important things in your life? In the last month, how often have you felt nervous or stressed? In the last month, how often have you felt confident about your ability to handle personal problems? 5. In the last month, how often have you felt that things were going your way? 6. In the last month, how often have you found that you could not cope with all the things you had to do? In the last month, how often have you been able to control irritations in your life? 8. In the last month, how often have you felt that you were on tops of things? 9. In the last month, how often have you been angry because of things that happened that were outside of your control? In the last month, how often have you felt that difficulties were piling up so high that you could not overcome them? 0.56 Factor 2 (α = 0.53) Variance explained, % Kaiser-Meyer-Olkin Measure of Sampling Adequacy 0.66 Bartlett`s Test of Sphericity <.05 Factor loading <0.33 were removed Internal consistency The Cronbach`s alpha coefficient of PSS-10 full scale was 0.77, indicates an acceptable level of internal consistency. As shown in Table 2, the internal consistency for factor 1 that represents perceived stress was acceptable (α= 0.79) but the internal consistency for factor 2 that represents coping ability was poor (α= 0.53). The analysis showed that Cronbach`s alpha coefficients did not improved by items elimination. Concurrent validity Concurrent validity of PSS was examined by the Pearson correlation with the subscales of DASS that measures stress, anxiety and depression. As shown in Table 3, there was a strong, positive correlation between PSS-10 and DASS-Stress, which was statistically significant, r(40)=.58, p <.001. PSS-10 also correlated moderately and significantly with and DASS-Anxiety and DASS- Depression. The findings of PSS-10 and DASS-21 correlations suggested concurrent validity of PSS- 10. The Study also found that DASS-Stress significantly correlated with DASS-Anxiety and DASS-Depression [r(40) = 0.80, p <.05]. This indicated that stressed subjects also experienced some degree of anxiety and depression. Table 3. Correlation between Total Scores of PSS-10 with DASS-21 Subscales, r Scales PSS-10 DASS-Stress DASS-Anxiety DASS-Depression PSS-10 1 DASS-Stress.58*** 1 DASS-Anxiety.47**.89*** 1 DASS-Depression.43**.80***.79*** 1 ** p <.01; *** p <.001 Comparison of PSS-10 with DASS-Stress The PSS scores of respondents were compared among different severity of stress according to total scores from DASS-Stress subscale, from normal to severe level of stress. One-way ANOVA analysis revealed that there was a significant effect of severity of stress on the total scores of PSS, F(3,38) = 4.21, p <.05. The assumption of homogeneity of variance was met. Post hoc comparisons using Tukey HSD test indicated that respondents with severe level of stress had higher PSS-10 score (M = 21.6, SD = 2.1) as compared to respondents who were normal (M = 16.6, SD = 3.3), p=.007. However, there were no significant

5 differences between mild and moderate level of stress with normal or severe level of stress. Taken together, these results suggested that severe level of stress do have an effect on PSS score. Table 4. Total Scores of PSS-10 by Severity of Stress According to DASS-Stress Severity of stress Normal Mild Moderate Severe N PSS-10 score, M (SD) 16.6 (3.3) 18.7 (1.5) 17.8 (1.0) 21.6 (2.1) DISCUSSION The findings of this study suggested that the Malay version of PSS-10 has adequate psychometric properties to be used among manufacturing industry workers to measure perceived stress. The mean PSS-10 score in this study (17.4) was slightly lower compared to other studies conducted in Malaysia among medical students (18.9) and diabetic patients (19.4) 12, 14. Statistical analysis showed that there is no significant differences of PSS-10 scores across socio-economic characteristics. Inconsistencies of PSS-10 scores across socio-economic factors had been observed in many studies. For instance, Andreou et al. 24 found that divorced or widows exhibited higher PSS-10 scores compared to singles or married couples but Lesage et al. 29 found that PSS-10 scores did not differ among marital status. Study by Cohen & Williamson 10 found that there was no difference of PSS-10 scores among genders but many studies reported that female respondents exhibited higher PSS-10 scores compared to male respondents 24, 30, 31. The factor analysis showed a 2-factor structure was consistent with the original version of PSS-10 by Cohen and Williamson 10 24, 27, and other studies 32. The first factor which is related with negative emotional reactions is called perceived stress while the second factor which is related with ability to cope with stressful situations is called coping 33. The 2-factor structure has accounted for 48.6% of the total variance which is slightly lower than Cohen`s original study of 48.9% 10 and a Malaysia study on railway worker population of 64.8% 13. As shown in Table 2, factor loadings lower than 0.33 were removed because a factor loading of 0.33 denotes that approximately 10% of the variable`s variance is accounted by the factor. In other words, items which could contribute more than 10% of the variance of a factor indicate that they are representative of that factor 34. Acceptable internal consistency was observed for PSS-10 full scale among manufacturing industry worker, as indicated by Cronbach`s Alpha value >0.7. Lee 11 found that Cronbach`s alpha coefficients of 19 papers he reviewed ranged from 0.74 to 0.89, suggesting that the internal consistency reliability of PSS-10 has been established. Our study revealed that factor 1 showed acceptable internal consistency (α=0.79) but factor 2 showed poor internal consistency (α=0.53). Lower internal consistency for factor 2 compared to factor 1 has been observed in several studies 12, 29, 35. Poor internal consistency for factor 2 might be due to random error attributable to respondents` misunderstanding of items 36. The concurrent validity of PSS-10 was reflected as the moderate correlations between PSS-10 and DASS Stress subscale, consistent with other studies 23, 24, 32. Cohen et al. 7 reported that there is some overlap between depressive symptomatology scale and PSS because the perception of stress may be a symptom of depression. The result supported the theory as PSS-10 showed moderate correlation with depression and anxiety in this study. For the comparison between PSS-10 scores and severity of stress, the result revealed that severely stressed subject would have higher PSS-10 scores in accordance with the study by Andreou et al. 24. There were some limitations in this study. Small sample size and the homogeneous sample of worker from only one manufacturing company may have affected the generalizability of the study. Gender bias was present in this study as all the respondents are male workers. Another limitation of this study was the absence of testretest reliability assessment of the scale and it is recommended to be included in future studies. CONCLUSION Despite the limitations mentioned, the findings of this study supported that the Malay version of PSS- 10 is a valid and reliable scale to measure perceived stress among manufacturing industry workers. ACKNOWLEDGEMENTS The research project was partly funded by Putra Grant of Universiti Putra Malaysia (GP- IPS/2013/ ). The authors would like to thank Ms. Sam Wei Yeng for her assistance in the translation of PSS-10 and all the respondents involved for their willingness to share their information. REFERENCES 1. Cohen S, Kessler RC, Gordon LU. Measuring stress: A guide for health and social scientists.

6 Measuring stress: A guide for health and social scientists. Oxford University Press; Cohen S, Janicki-Deverts D, Miller GE. Psychological stress and disease. The Journal of the American Medical Association 2007; 298(14): Hammen C. Stress and depression. Annual Review of Clinical Psychology 2005; 1: Lloyd, C., Smith, J., & Weinger, K. Stress and diabetes: A review of the links. Diabetes Spectrum 2005; 18: Mohd Rafee, B.B., Lim, C.S., Sam, W.Y & Nazmin, H. Practical guide to OSH risk management. Understanding, evaluating and implementing HIRARC at workplace. Bangi, Malaysia: NIOSH, Lovibond SH, Lovibond PF. Manual for the depression anxiety and stress scales, 2nd edition. Behav Res Ther. Psychology Foundation of Australia; 1995; 33(3): Cohen S, Kamarck T, Mermelstein R. A global measure of perceived stress. J Health Soc Behav 1983; 24(4): Peacock EJ, Wong PP. The Stress Appraisal Measure (Sam): A Multidimensional Approach To Cognitive Appraisal. Stress Med 1990; 6: Schulz P, Schlotz W. Trierer Inventar zur Erfassung von chronischem Streß (TICS): Skalenkonstruktion, teststatistische Überprüfung und Validierung der Skala Arbeitsüberlastung. Diagnostica. 1999; 45(1): Cohen S, Williamson GM. Perceived stress in a probability sample of the United States. In: Spacapan S, Oskamp S, editors. The Social Psychology of Health. Sage; 1988: Lee EH. Review of the psychometric evidence of the perceived stress scale. Asian Nurs Res 2012; 6: Al-Dubai SAR, Alshagga MA, Rampal KG, Sulaimaan NA. Factor structure and reliability of the Malay version of the perceived stress scale among Malaysian medical students. Malaysian J Med Sci 2012; 19(3): Al-Dubai SAR, Ganasegeran K, Barua A, Rizal A, Rampal KG.Evaluation of psychometric properties of the malay version perceived stress scale in two occupational settings in malaysia. Annals of Med and Health Sci Research 2014; 4(2): Gillani SW, S SAS, Sari YO, Sarriff A, Amin A, Baig M. Perceived Stress Scale: Psychometric Validation for Malaysian Diabetic Patients. British J Pharmaceutical Research 2011; 1(4): Hazrina NM, Ahmad AA. Validity study of Malay-translated version of Perceived Stress Scale. Malaysian J Forensic Sci 2012; 3(1): Prime Minister`s Department Malaysia. Annual Report of the Economic Transformation Programme Malaysia [Internet]. EPPO Bulletin Available from: 13/upload/ENG/ETP2013_ENG_full_version.p df 17. Blaug R, Kenyon A, Lekhi R. Stress at work: A report prepared for the work foundation s principal partners. London, England: The Work Foundation 2007: Leka S, Griffiths A, Cox T. Work organization & stress. Geneva: World Health Organization; Cocks K, Torgerson DJ. Sample size calculations for pilot randomized trials: A confidence interval approach. J Clin Epidemiol 2013; 66(2): Chan RCK, Xu T, Huang J, Wang Y, Zhao Q, Shum DHK, et al. Extending the utility of the Depression Anxiety Stress scale by examining its psychometric properties in Chinese settings. Psychiatry Research 2012; 200(2-3), Tonsing KN. Psychometric properties and validation of Nepali version of the Depression Anxiety Stress Scales (DASS-21). Asian J Psychiatr 2014; 8: Vignola RCB, Tucci AM. Adaptation and validation of the depression, anxiety and stress scale (DASS) to Brazilian Portuguese. J Affective Disorders 2014; 155: Al-Dubai SAR, Barua A, Ganasegeran K, Jadoo SA, Rampal KG. Concurrent Validity of the Malay Version of Perceived Stress Scale ( PSS- 10 ). ASEAN J Psychiatry 2014; 15(1): Andreou E, Alexopoulos EC, Lionis C, Varvogli L, Gnardellis C, Chrousos GP, et al. Perceived Stress Scale: Reliability and validity study in Greece. Int J Environ Res Public Health 2011; 8: Musa R, Fadzil MA, Zain Z. Translation, validation and psychometric properties of Bahasa Malaysia version of the Depression

7 Anxiety and Stress Scales (DASS). Asean J Psychiatry 2007; 8(2): Edimansyah BA, Rusli BN, Naing L, Mohamed Rusli BA, Winn T, Tengku Mohamed Ariff BRH. Self-perceived depression, anxiety, stress and their relationships with psychosocial job factors in male automotive assembly workers. Ind Health 2008; 46(1): Ng S. Validation of the 10-item Chinese perceived stress scale in elderly service workers: one-factor versus two-factor structure. BMC Psychol 2013; 1(1): Tavakol M, Dennick R. Making sense of Cronbach s alpha. Int J Med Educ 2011; 2: Lesage F-X, Berjot S, Deschamps F. Psychometric properties of the French versions of the Perceived Stress Scale. Int J Occup Med Environ Health 2012; 25(2): Leung DY, Lam T-H, Chan SS. Three versions of Perceived Stress Scale: validation in a sample of Chinese cardiac patients who smoke. BMC Public Health 2010; 10: Remor E. Psychometric properties of a European Spanish version of the Perceived Stress Scale (PSS). Span J Psychol 2006; 9(1): Loubir D., Serhier Z, Battas O, Agoub M, Othmani MB. Evaluation of psychometric properties of the Arabic version of PSS stress measuring scale in the Moroccan population. SAGE Open 2014; 4: Hewitt PL, Flett GL, Mosher SW. The Perceived Stress Scale: Factor structure and relation to depression symptoms in a psychiatric sample. J Psychopathology and Behavioral Assessment 1992; 14(3): Ho R. Handbook of Univariate and Multivariate Data Analysis with IBM SPSS, Second Edition [Internet]. CRC Press Available from: AQBAJ&pgis=1 35. Reis RS, Hino AAF, Añez CRR. Perceived stress scale: reliability and validity study in Brazil. J Health Psychol 2010; 15: McCrae RR, Kurtz JE, Yamagata S, Terracciano A. Internal consistency, retest reliability, and their implications for personality scale validity. Pers Soc Psychol Rev 2011; 15(1):