Factor Structure and Concurrent Validity of the World Assumptions Scale

Transcription

1 Journal of Traumatic Stress, Vol. 20, No. 3, June 2007, pp ( C 2007) Factor Structure and Concurrent Validity of the World Assumptions Scale Ask Elklit Department of Psychology, University of Aarhus, Aarhus, Denmark Mark Shevlin School of Psychology, University of Ulster (Magee), Londonderry, UK Zahava Solomon The Bob Shapell School of Social Work, Tel Aviv University, Tel Aviv, Israel Rachel Dekel School of Social Work, Bar-Ilan University, Bar-Ilan, Israel The factor structure of the World Assumptions Scale (WAS) was assessed by means of confirmatory factor analysis. The sample was comprised of 1,710 participants who had been exposed to trauma that resulted in whiplash. Four alternative models were specified and estimated using LISREL A correlated 8-factor solution was the best explanation of the sample data. The estimates of reliability of eight subscales of the WAS ranged from.48 to.82. Scores from five subscales correlated significantly with trauma severity as measured by the Harvard Trauma Questionnaire, although the magnitude of the correlations was low to modest, ranging from.08 to.43. It is suggested that the WAS has adequate psychometric properties for use in both clinical and research settings. Traumatic events affect various aspects of victims lives, including physical, behavioral, social, emotional, and cognitive functioning (Slaikeu, 1990). Cognitive changes have attracted attention, as these changes may be important for the development and maintenance of emotional problems, and as such, they may have considerable therapeutic implications (Bard & Sangrey, 1986; Horowitz, 1986; Foa & Riggs, 1993). Foa, Cashman, Jaycox, and Perry (1999) suggest that two cognitions are particularly associated with the development of posttraumatic stress disorder (PTSD): (a) the world is completely unsafe, and (b) the individual is incompetent. Ehlers and Clark (2000) propose a sim- ilar cognitive mechanism. In this model, PTSD develops when individuals process the trauma in a way that leads to a sense of threat, either through negative appraisal of the trauma or because of a disturbance in the trauma memory. In the last decade, there have been a number of attempts to develop adequate measures to assess such changes in traumatized populations. The World Assumptions Scale (WAS; Janoff-Bulman, 1989) is the most widely used measure of beliefs and attitudes after traumatic events. The scale is closely linked to the Janoff-Bulman theory of shattered assumptions (1992) that has won wide recognition within the trauma field. Based on observations of victims, This study was supported by the Danish Israeli Foundation in memory of Josef and Regine Nachemsohn and by the Research Foundation of the University of Aarhus. Correspondence concerning this article should be addressed to: Ask Elklit, Department of Psychology, University of Aarhus, Jens Chr. Skous Vej 4, DK 8000 Aarhus, Denmark. aske@psy.au.dk. C 2007 International Society for Traumatic Stress Studies. Published online in Wiley InterScience ( DOI: /jts

2 292 Elklit et al. Janoff-Bulman proposed that survivors assumptive world might be challenged and even shattered following traumatic events. More specifically, she proposed three primary categories, each of which builds on several assumptions. The first primary category is Benevolence of the World, which consists of two basic assumptions: the benevolence of the impersonal world and the benevolence of people corresponding to belief that the world is a good place and people are basically good and caring. The second primary category is Meaningfulness of the World, which involves people s beliefs about the distribution of good versus bad outcomes. Three principles guide our understanding: (a) justice that we get what we deserve, (b) controllability the extent to which people engage in appropriate behavior determines what will happen to them, and (c) randomness outcome is a matter of pure chance. The three principles are not considered mutually exclusive; people are apt to believe in the operation of all three principles to a greater or lesser extent. The third primary category is worthiness of self, which includes three dimensions: (a) self-worth the extent to which people perceive themselves as good, moral, decent individuals; (b) self-controllability the extent to which people see themselves as engaging in appropriate, precautionary behaviors to control outcomes (whatever the final outcome might be); and (c) luck an elusive self-perception that allows individuals to believe that they will be protected from ill fortune and come out ahead. The theory proposes that following traumatic events, individuals are confronted with salient, critical experiences and information, which are incongruent with their preexisting assumptions. Victims face a difficult cognitive dilemma of integrating the new overwhelming information into old assumptions or revising them so that they fit the new trauma information. To assess these basic assumptions about the self and the world the WAS was devised. The WAS consists of eight primary dimensions, or subscales, each comprised of four items that correspond to the dimensions described above: self-worth, luck, justice, randomness, benevolence of people, benevolence of the world, self-control, and control. To date, all published studies using the WAS (for a detailed review, see Dekel, Solomon, Elklit, & Ginzburg, 2004) have used the eight subscales suggested by the author, or a combination of the eight subscales (Schwartzberg & Janoff-Bulman, 1991) resulting in three secondary dimensions: benevolence of the world (sum of benevolence of people and benevolence of the world scores), meaningfulness (sum of justice, randomness, and control scores), and self-worth (sum of self-worth, luck, and self-control). The WAS has been widely used to explain the psychological reactions to traumatic events such as combat-related stress (Dekel et al., 2004), torture (Magwaza, 1999), and natural disaster (Bödvarsdóttir & Elklit, 2004). However, the psychometric properties of the scale have not been examined since Janoff-Bulman, author of the scale (1989), conducted an exploratory factor analysis based on the responses of 356 subjects (without any background information except gender). They reported a factor structure similar to the proposed model (with the exception that the benevolence of world and benevolence of people items loaded on one factor, rather than two) and the subscale reliabilities were between.66 and.76. The current study had two main aims. The first aim was to examine the factor structure of the WAS by means of confirmatory factor analysis. Four models were specified and estimated; a single factor model, a correlated 8- factor model representing the primary factors of the WAS, a correlated 3-factor model representing the secondary constructs, and a second-order factor model with the eight firstorder primary factors loading on the three second-order, or secondary, factors. The second aim was to establish the concurrent validity of the WAS by examining the association between its dimensions and self-reported severity of trauma-related symptoms. Foa, Ehlers, Clark, Tolin, and Orsillo (1999) reported significant negative correlations between both trauma-related cognitions and PTSD severity and the WAS dimensions of self-worth (r =.40), luck (r =.25), self-control (r =.16), and benevolence of world (r =.19); benevolence of people was only associated with trauma-related cognitions. A very similar pattern of significant correlations was also reported by Solomon, Iancu, and Tyano (1997) who reported that self-worth (r =.39), luck (r =.12), benevolence of people

3 Factor Structure of the World Assumptions Scale 293 (r =.25), and benevolence of world (r =.19) were negatively related to PTSD severity. Dekel et al. (2004) found that current PTSD status of Israeli veterans was associated 1 only with scores for benevolence of people (r =.18) and self-worth (r =.33). On the basis of previous findings it was predicted that significant correlations in the range of r =.15 to r =.40 would be found between self-reported severity of trauma-related symptoms and scores for self-worth, luck, benevolence of people, benevolence of world, and self-control. METHOD Participants There were 1,710 recruited participants. The mean age was 43 years (SD = 10) and 79% (N = 1349) were women. Men were significantly older than women, t(1700) = 3.58, p <.001, although the mean difference was small (2.19 years). The participants had been exposed to trauma that had resulted in whiplash; this was on average 62 months (SD = 64) prior to participating in the study. They were recruited through the Danish Society for Polio, Traffic and Accident Victims. The society generally receives referrals from the Danish National Health Service and other health related sources. All society members who suffered from whiplash (N = 2,320) were contacted with a response rate of 74%. The women:men ratio of the final sample closely matched the complete patient group (approximately 4:1); it also correlated with findings from epidemiological studies that have shown that women have a higher risk of developing and maintaining whiplash-related symptoms (Harder, Veilleux, & Suissa, 1998). All participants were contacted by mail and invited to participate in the study by completing The World Assumptions Scale and the Harvard Trauma Questionnaire. Almost all participants (N = 1,527, 89.9%) sustained a whiplash injury through a motor vehicle accident and half (N = 831, 50%) sustained other physical injuries. A quar- 1 The original presented the results in terms of an ANOVA. We expressed the mean difference in terms of an effect size correlation (see Cohen, 1998). ter of all participants (N = 426, 25.4%) were hospitalized after the accident, and for those the mean length of stay was 7 days. Almost half the participants contacted a doctor within 24 hours (N = 829, 49%), with smaller numbers waiting up to 48 hours (N = 407, 24%). Almost all the participants (N = 1,601, 95.2%) had sought medical help within 4 weeks of the accident. The diagnosis of whiplash was given on the same day for almost half the participants (N = 779, 45.6%). Data were missing on all WAS items although the percentage of missing data on each item was small ( %). Missing data were imputed using the EM algorithm, which has been demonstrated to be an effective method of dealing with missing data (Bunting, Adamson, & Mulhall, 2002) and all analyses were conducted using the 1,710 participants. Based on diagnosis using the Harvard Trauma Questionnaire, 42.2% of the participants was classified as having PTSD, and 32.0% as having subclinical PTSD (defined as missing the full diagnosis by one symptom). Although the percentage classified as having PTSD is relatively large, there is evidence that PTSD can be a long-term consequence of whiplash. Blanchard et al. (1996) reported that 33% of whiplash victims initially diagnosed with PTSD still met the diagnostic criteria one year later. They also reported that there was little additional remission after another 6 months. Based on a prospective study, Mayou, Tyndel, and Bryant (1997) reported that approximately 10% of the sample were still diagnosed with PTSD 5 years after the accident. Measures The World Assumptions Scale (Janoff-Bulman, 1989) is a 32-item checklist of assumptions about beliefs that respondents are asked to respond to on a 6-point Likert scale anchored by the respondent options of strongly disagree and strongly agree. The scale generates eight subscale scores with possible scores ranging from 6 to 24 with higher scores indicating higher beliefs in that assumption. Estimates of reliability of each of the subscales have tended to be reasonable. Janoff-Bulman (1989) reported alphas ranging from

4 294 Elklit et al , which were similar to those (.66.76) reported by Dekel et al. (2004). The Harvard Trauma Questionnaire Part IV (HTQ; Mollica et al., 1992) assesses both the symptoms specified in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994) and the culture-specific symptoms associated with PTSD. The scale yields both a PTSD diagnosis according to DSM-IV criteria and a measure of PTSD symptom severity. The 30 items are answered on a 4-point Likert scale, 1 = not at all, 2= a little, 3= quite a bit, and 4 = all the time. The summed score provides a score for symptom severity. The first 16 items, which were used in this study, were derived directly from the DSM-IV criteria for PTSD 2 and are divided into three subscales that correspond to the three main symptom groups of PTSD (possible range of scores in parenthesis): reexperiencing (4 16), avoidance (7 28), and arousal (5 20). Possible total scale scores range from 16 to 64. Similar to Mollica et al., Bödvarsdóttir and Elklit (2004) reported high estimates of reliability for each of the subscales: reexperiencing, α =.86; avoidance, α =.79; and arousal, α =.87; and the scale as a whole, α =.94. Following the DSM-IV, the diagnosis of PTSD was made if participants satisfied all of the following criteria: (a) endorsed at least one reexperiencing symptom, (b) endorsed at least three avoidance symptoms, and (c) endorsed at least two arousal symptoms. A symptom was rated as endorsed if the item corresponding to the symptom was scored 3 (quite a bit) or greater. This is a more conservative approach that that taken by others, such as Foa, Cashman, Jaycox, and Perry (1997) who used scores of 1 or greater for symptom endorsement. It should be noted that diagnoses based on self-report may be less valid than those based on clinical interview. Data Analysis Four confirmatory factor models were specified and estimated using LISREL 8.72 (Jöreskog & Sörbom, 2005a). 2 The HTQ uses one item to assess both psychological (B4) and physiological (B5) reactions to events that symbolize or resemble aspects of the traumatic event. A covariance matrix and an asymptotic weight matrix (the distribution of all WAS items deviated significantly from normality in terms of skewness and kurtosis) were computed using PRELIS 2.72 (Jöreskog & Sörbom, 2005b) and the parameters estimated using maximum likelihood. The use of an asymptotic weight matrix allows for weaker assumptions regarding the distribution of the observed variables and results in improved fit and test statistics (Curran, West, & Finch, 1996; Satorra 1992). Following the guidelines suggested by Hoyle and Panter (1995), the goodness of fit for each model was assessed using the Satorra Bentler scaled chi-square (S Bχ 2 ), the Incremental Fit Index (IFI; Bollen, 1989), and the Comparative Fit Index (CFI; Bentler, 1990). A nonsignificant chi-square and values greater than.90 for the IFI and CFI are considered to reflect acceptable model fit. In addition, the Root Mean Square Error of Approximation (RMSEA; Steiger, 1990) with 90% confidence intervals (90% CI) were reported, where a value less than.05 indicates close fit and values up to.08 indicating reasonable errors of approximation in the population (Jöreskog & Sörbom, 1993). The standardized root-mean-square residual (SRMR; Jöreskog &Sörbom, 1981) has been shown to be sensitive to model misspecification and its use as recommended by Hu and Bentler (1999). Values less than.08 are considered to be indicative of acceptable model fit (Hu & Bentler, 1998). The comparative fit of the models was assessed using the Expected Cross Validation Index (ECVI; Browne & Cudeck, 1989) and the Akaike Information Criterion (AIC; Akaike, 1987), indices used for the purposes of model comparison, with the smallest value being indicative of the best fitting model. Model 1 was a 1-factor model with all the items loading on a general factor of world assumptions. Model 2 represented the secondary categories as an 8-factor model with the four items loading on each of their respective factors. The factors were specified as correlated and no cross-factor loadings were included. Model 3 represented the primary categories as a 3-factor model with the benevolence of world and benevolence of people items loading on the benevolence of the world factor, justice, randomness, and control items loading on the meaningfulness factor, and

5 Factor Structure of the World Assumptions Scale 295 the self-worth, luck, and self-control items loading on the self-worth factor. The factors were specified as correlated and no cross-factor loadings were included. Model 4 was a second-order factor analysis with the eight secondary categories as first-order factors, and the three primary categories as three second-order factors. The first-order benevolence of world and benevolence of people factors were specified to load on the second-order benevolence of the world factor, the first-order justice, randomness, and control factors were specified to load on the second-order meaningfulness factor, and the first-order self-worth, luck, and self-control factors were specified to load on the second-order selfworth factor. The second-order factors were specified as correlated and there were no first- or second-order crossloadings. No models were specified to include correlated errors and cross-factor loadings were all constrained to zero. RESULTS The means and standard deviations for the WAS are presented in Table 1. In general, the mean scores for each subscale tended to decrease in relation to PTSD severity. The means and standard deviations for the HTQ are presented in Table 2. For each of the subscales and the total HTQ scores, the mean scores decrease in relation to PTSD severity. The distribution of each of the subscales deviated significantly from normality in terms of skew. The scores for the reexperiencing and avoidance subscales were negatively skewed indicating a clustering of scores at the lower end of the possible range of scores. The scores for the arousal subscale were positively skewed indicating a clustering of scores at the upper end of the possible range of scores. The distribution of the total scores was normally distributed. The fit indices are reported in Table 3. Based on the RM- SEA, IFI, CFI, and the SRMR, only Model 2 and Model 4 were judged to exhibit acceptable model fit, whereas the fit indices for Models 1 and 3 showed they were poor models. Although the chi-square for Models 2 and 4 were large relative to the degrees of freedom, and statistically significant, this should not lead to the rejection of the models as the large sample size increases the power of the test Table 1. Descriptive Statistics for the World Assumptions Scale by Posttraumatic Stress Disorder (PTSD) Status PTSD Status M SD Self-worth PTSD absent Subclinical PTSD PTSD present Total Luck PTSD absent Subclinical PTSD PTSD present Total Justice PTSD absent Subclinical PTSD PTSD present Total Benevolence of people PTSD absent Subclinical PTSD PTSD present Total Benevolence of world PTSD absent Subclinical PTSD PTSD present Total Self-control PTSD absent Subclinical PTSD PTSD present Total Control PTSD absent Subclinical PTSD PTSD present Total Random PTSD absent Subclinical PTSD PTSD present Total (Tanaka, 1987). Models 2 and 4 also had the lowest ECVI and AIC values. Models 1 and 3 are nested in Model 2 and Model 4, so likelihood ratio difference tests 3 are possible to determine statistical difference between the fit of the models. Model 2 was a significantly better explanation of the data than Model 1 ( S-Bχ 2 = 5875, df = 28, p =.001) and Model 3 ( S-Bχ 2 = 3673, df = 25, 3 Satorra and Bentler (2001) have developed a scaled difference chi-square statistic to compare the S B χ 2 for nested models and this statistic can be calculated using a program by John Crawford, which be downloaded from psy086/dept/psychom.htm

6 296 Elklit et al. Table 2. Descriptive Statistics for the Harvard Trauma Scale by Posttraumatic Stress Disorder (PTSD) Status PTSD Status M SD Reexperiencing PTSD absent Subclinical PTSD PTSD present Total Avoidance PTSD absent Subclinical PTSD PTSD present Total Arousal PTSD absent Subclinical PTSD PTSD present Total Total PTSD absent Subclinical PTSD PTSD present Total p =.001), and Model 4 was a significantly better explanation of the data than Model 1 ( S-Bχ 2 = 4348, df = 11, p =.001) and Model 3 ( S-Bχ 2 = 3118, df = 8, p =.001). Models 2 and 4 are not nested so a likelihood ratio difference test is not possible to determine which offers the best fit. However, Model 2 had a lower RMSEA (the upper Table 3. Fit Indices for the Alternative Models of the World Assumptions Scale Index Model 1 Model 2 Model 3 Model 4 S Bχ df p <.001 <.001 <.001 <.001 RMSEA % CI ECVI AIC IFI CFI SRMR Note.IFI= Incremental Fit Index; CFI = Comparative Fit Index; RMSEA = Root Mean Square Error of Approximation; CI = confidence interval; SRMR = standardized root-mean-square residual; ECVI = Expected Cross Validation Index; AIC = Akaike Information Criterion. Criteria for acceptable model fit are p <.05 for S Bχ 2,IFI,andCFI>.90, RMSEA and SRMR <.08, and lowest value for the ECVI and AIC indicates the best-fitting model. Figure 1. Correlated 8-factor model of the World Assumptions Scale. Small arrows symbolize measurement error. 90% confidence interval for Model 2 is less than the lower 90% confidence interval for Model 4), a lower ECVI and AICvalue,highervaluesfortheIFIandCFI,andalower SRMR value. Based on this, it is proposed that Model 2 represents an adequate description of the data, and is the best of the alternative models. The model is presented in Figure 1. However, the adequacy of Model 2 must also be considered in terms of the parameter estimates. The factor loadings for Model 2 are presented in Table 4. Although all the loadings were statistically significant (p <.05), the magnitude of eight loadings are considered fair to poor (<.45), 10 are considered excellent (>.71), and the remaining are good to very good (Comrey & Lee, 1992). The factor correlation matrix is presented in Table 5. Most of the correlations are statistically significant (p <.05). However, there is variability in the magnitude and direction of the correlations. The highest correlations are between the benevolence of people and benevolence of world variables (r =.75), and the control and justice

7 Factor Structure of the World Assumptions Scale 297 Table 4. Standardized Factor Loadings for the Factor Model of the World Assumptions Scale (WAS) Benevolence Benevolence Self-worth Luck Justice of people of world Self-control Control Random SMC WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS WAS Alpha Note. SMC= Squared multiple correlation. Table 5. Factor Correlations from the Confirmatory Factor Analysis of the World Assumptions Scale Benevolence Benevolence Self-worth Luck Justice of people of world Self-control Control Random Luck Justice Benevolence of people Benevolence of world Self-control Control Random p <.05.

8 298 Elklit et al. Table 6. Correlations Between WAS Subscale Scores and HTQ Scores HTQ HTQ HTQ HTQ Reexperiencing Avoidance Arousal Total Score N = 1626 N = 1538 N = 1631 N = 1,435 Self-worth Luck Justice Benevolence of people Benevolence of world Self-control Control Random Note. WAS= World Assumptions Scale; HTQ = Harvard Trauma Questionnaire. The sample sizes are different due to pairwise deletion of cases with missing data on the HTQ. p <.05. (r =.63) variables. Five correlations did not differ significantly from zero and another seven correlations were less than ±.20. The reliability estimates ranged from.48 to.82, with a mean of.64. Reliability analysis indicates acceptable internal reliability for three subscales; self-worth (α =.77), luck (α =.82), and benevolence of world (α =.74). Cronbach s alphas for subscales are presented in Table 4. The reliability of each item, the squared multiple correlation (SMC) is presented in Table 4. The SMCs range from.02 to.79. The WAS subscales were used as predictors of trauma severity to assess the concurrent validity of the subscales. The reexperiencing, avoidance, arousal, and total scale scores of the HTQ was used as the measure of trauma severity. The correlations are reported in Table 6. Table 6 shows that scores for self-worth, luck, benevolence of people, and benevolence of world were all significantly negatively correlated with each of the three HTQ scale scores and the total HTQ scores. Randomness was significantly positively correlated with each of the three HTQ scale scores and the total HTQ scores. It should be noted that given the sample size correlations greater than r =±.08 will be statistically significant, so statistically significant does not imply important or meaningful associations. None of the correlations associated with justice, self-control, and control was statistically significant. DISCUSSION The aim of this study was to assess the psychometric properties of the WAS. Four alternative models of the WAS were specified and estimated. Based on fit indices an 8- factor model (Model 2) was found to provide an adequate fit to the data and was considered to be better than the alternative models. This supports Janoff-Bulman s (1989) conceptualization of the secondary constructs of the WAS, but fails to support the proposed structure of the three primary constructs. Model 3 specified the primary constructs as three first-order factors and the fit of this model was poor. When the primary constructs were modeled as second-order factors (Model 4), the fit of the model was significantly improved although fit of this model was poorer than Model 2. This suggests that the eight first-order factors can be used to represent a smaller number of second-order factors, although there is little support for the structure suggested by the scale s author. The correlations between the justice and control subscales indicate that they may represent an underlying second-order factor, whereas the correlations among the benevolence of world, benevolence of people, self-worth, and luck subscales suggest another factor. The number and structure of any higher-order factors may be the focus for further research. The eight subscales derived from Model 2 generated scores with varied reliability. The reliability of the subscales

9 Factor Structure of the World Assumptions Scale 299 ranged from.48 to.82. with self-worth and luck having the highest reliability. It would be desirable if the other subscales had higher reliability. This could be achieved by refining item content for those items with low factor loadings or squared multiple correlations (for example, 1 and 3), although increasing the number of items for each subscale may be an easier approach as the subscales with the lowest factor loadings did not have the lowest reliability. Because the WAS was created to measure disturbed beliefs as a result of exposure to trauma, it would be expected that the subscales should be associated with self-reported severity of trauma related symptoms. Table 6 showed that the scores for self-worth, luck, benevolence of people, and benevolence of world were all significantly negatively correlated, and randomness significantly positively correlated, with each of the three HTQ scale scores and the total HTQ scores. From a theoretical point of view, these correlations seem to make sense. A negative outlook on the world, the feelings of being subjected to an ill fate, and not being a worthy person are coherent attributions that reflect common societal reactions to victims. As such, they are stereotypes that are easily available to victims who may end up by identifying with these schemata if the recovery process does not succeed (Lerner, 1970, 1980). It should also be noted that (with the exception of self-worth) although the correlations were statistically significant, the magnitude of the correlations indicates only a limited degree of shared variance with trauma symptom severity (1% 8%). Foa et al. (1999) used the WAS as part of the validation process of the Posttraumatic Cognitions Inventory (PTCI). Based on correlations between the WAS and the PTCI they stated that the WAS has very good internal consistencies, but its correlations with measures of psychopathology were low to moderate. Furthermore, they found that none of its subscales showed any substantial correlations with PTSD severity, probably because the WAS was developed to assess cognitions affected by trauma in general, and was not specifically designed to measure cognitions associated with chronic PTSD. Based on their results, they suggested that the WAS is of limited use as a clinical instrument to measure cognitions associated with PTSD (p. 311). The results of the current study do not fully support these conclusions as the correlations reported for selfworth, benevolence of people, and randomness were higher than those reported by of Foa et al. (1999) whereas the other correlations were very similar in magnitude. However, the magnitude of the correlations, and the fact that only five subscales were significantly related to HTQ scores, question the utility of using the entire WAS scale in a clinical setting. Based on this study and previously reported findings, it does not appear that assumptions related to justice or control were significantly related to trauma symptom severity. The modest degree of shared variance for WAS subscales and trauma symptom severity may have several explanations: (a) The WAS subscales are unreliable; (b) various trauma events elicit specific assumptions that are relevant to the situation (e.g., justice in the case of physical assault, randomness after an accident, self control after a date rape); and (c) there were theoretical limitations, i.e., perhaps some of the assumptions do not govern our behavior or thinking in any particular degree, but are more like rationalizations that fit social schemes. In addition, the centrality of each assumption and the connections among the assumptions may depend on personality structure: We may have assumptions that are antagonistic perhaps without knowing it or without being bothered by them. All the possible explanations points to the necessity of doing more basic research on the role of beliefs systems in everyday life and after trauma. Any future studies in this area could incorporate design elements to overcome the limitations of this study. First, clinical interview-based diagnosis of PTSD would be superior to those based on self-report. Second, a longitudinal prospective study would allow the changes in beliefs to be explored after establishing a baseline score on all dimensions. Third, the inclusion of a control group would allow a test of differences of basic assumptions between those who have, and have not been, exposed to any trauma. In conclusion, the WAS was found to be a multifactorial measure consisting of eight correlated first-order factors. The reliability of the subscales varied from.48 to.82, but could be improved by increasing the number of items used to measure each construct. The subscales correlated

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