Personality and Social Psychology Dimensionality of stress experiences: Factorial structure of the Perceived Stress Questionnaire (PSQ) in a population-based Swedish sample MICHAEL R € ONNLUND, 1 PETER VESTERGREN, 2 ANDREAS STENLING, 1 LARS-G € ORAN NILSSON, 3,4 MAUD BERGDAHL 5 and JAN BERGDAHL 1,5 1 1 Department of Psychology, Ume  a University, Sweden 2 Department of Science and Mathematics Education, Ume  a University, Sweden 3 Aging Research Center, Karolinska Institutet, Sweden 4 Ume  a Center for Functional Brain Imaging, Ume  a University, Sweden 5 Department of Clinical Dentistry, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway R€ onnlund, M., Vestergren, P., Stenling, A., Nilsson, L.-G., Bergdahl, M. & Bergdahl, J. (2015). Dimensionality of stress experiences: Factorial structure of the Perceived Stress Questionnaire (PSQ) in a population-based Swedish sample. Scandinavian Journal of Psychology. We investigated the factorial structure of the Perceived Stress Questionnaire (PSQ-recent; Levenstein, Prantera, Varvo et al., 1993) in a large (n = 1516; 35–95 years) population-based Swedish sample Nilsson, Adolfsson, B€ ackman et al., 2004; Nilsson, B€ ackman, Erngrund et al., 1997). Exploratory principal components analysis (PCA) was conducted on a first, randomly drawn subsample (n = 506). Next, the model based on the PCA was tested in a second sample (n = 505). Finally, a third sample (n = 505) was used to cross-validate the model. Five components were extracted in the PCA (eigenvalue > 1) and labeled “Demands,”“Worries/Tension,”“Lack of joy, ”“Conflict,” and “Fatigue,” respectively. Twenty-one out of the 30 original PSQ items were retained in a confirmatory factor analysis (CFA) model that included the five (first-order) factors and, additionally, a general (second-order) stress factor, not considered in prior models. The model showed reasonable goodness of fit[v 2 (184) = 511.2, p < 0.001; CFI = 0.904; RMSEA = 0.059; and SRMR = 0.063]. Multigroup confirmatory factor analyses (MGCFA) supported the validity of the established model. The results are discussed in relation to prior investigations of the factorial structure of the PSQ. Key words: perceived stress, confirmatory factor analysis, multigroup analysis. Michael R€ onnlund, Department of Psychology, Ume  a University, S-90187 Ume  a, Sweden. E-mail: michael.ronnlund@psy.umu.se INTRODUCTION Stress is often regarded to involve adaptive reactions of organ systems in response to physical or mental stressors. Motivated by the concern about the high prevalence of stress-related diseases in modern society, much research has been devoted to the effects of stress on physical and mental aspects of health (e.g., Kessler, 1997, Schneiderman, Ironson & Siegel, 2005) and cognitive performance (e.g., Lupien, Maheu, Tu, Fiocco & Schramek, 2007; R€ onnlund, Sundstr€ om, Eriksson S€ orman & Nilsson, 2013; Rosnick, Small, McEvoy, Borenstein & Mortimer, 2007). Psychologically, stress is assumed to result from an imbalance between the demands encountered by the individual and his or her perceived ability to cope with those demands (Lazarus & Folkman, 1984). In line with this focus on subjective appraisal, questionnaires that target perceived demands and psychological stress reactions (e.g., worries) have been developed. One such measure is the Perceived Stress Questionnaire (PSQ; Levenstein et al., 1993). The PSQ was developed based on observations by experienced clinicians and patients of life situations that trigger symptoms and was specifically intended for psychosomatic research (Levenstein, et al., 1993). The 30 items were formulated to describe experiences of stress applicable across a variety of situations (e.g., “you feel tense;”“you feel that you have too many decisions to make”) and emphasize cognitive perceptions rather than emotional states or speci fic life events. For each item the respondent is requested to rate the frequency of occurrence of the described experience on a four-point scale (from “almost never” to “usually”) during the last month (“PSQ-recent”) or during the last year (“PSQ-general”). The PSQ was developed in English and Italian, and has been translated into, for example, Spanish (Sanz-Carillo, Garc  ıa-Campayo, Rubio, Santed & Montoro, 2002), Thai (Ross, Zeller, Srisaeng, Yimmee, Somchid & Sawatphanit, 2005), and German (Fliege, Rose, Arck et al., 2005). As concerns concurrent validity, the total score (“PSQ index”) in Levenstein et al. (1993) was shown to correlate (r = 0.56 and 0.73, respectively, for the recent and general versions) with Cohen’s Perceived Stress Scale (PSS; Cohen, Kamarck & Mermelstein, 1983). Also, the PSQ-index was associated with eight out of nine scales of the Job Stress Survey (rs = 0.29–0.69; Holmstr€ om, Molander, Jansson & Barnekow-Bergqvist, 2008). Evidence in regard to construct validity include substantial correlations between recent and general PSQ-indexes and trait anxiety (using STAI as a measure; Levenstein et al., 1993; Sanz-Carillo et al., 2002) and depressive symptoms (BDI; Levenstein et al. 1993; Sanz-Carillo et al., 2002). In addition, the PSQ-index has been found to differentiate between various patients groups and controls (Fliege et al., 2005) and to be sensitive to intra-individual change as judged from treatment effects (Bergdahl, Larsson, Nilsson, Riklund  Ahlstr€ om & Nyberg, 2005; Fliege et al., 2005). The focus of the present study is on another aspect of construct validity, namely the factorial structure of the PSQ. The aim was to examine the factor structure for a Swedish version of the questionnaire. A prior study based on PSQ (recent) established 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 © 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd Scandinavian Journal of Psychology, 2015 DOI: 10.1111/sjop.12214 SJOP 12214 Dispatch: 25.3.15 CE: Wiley Journal Code Manuscript No. No. of pages: 7 PE: Jegadeesh