Factor Analytic Investigations Research Articles

The factor structure and subscale properties of the pain catastrophizing scale: are there differences in the distinctions?

The purpose of this study was to evaluate the dimensionality of PCS responses in a sample of patients with chronic pain (N = 8370). Data were randomly halved, and results were cross-validated. Both traditional factor analysis and traditional factor analyses were conducted. Findings based on common factor analyses and on bifactor analyses supported the essential unidimensionality of PCS responses. In the bifactor analyses, the general factor accounted for 96% of the explained common variance in the modeling sample. After extracting the general factor, helplessness, magnification, and rumination subscales accounted for 7.0%, 0.0%, and 15%, respectively. The results do not necessarily disconfirm helplessness, magnification, and rumination as clinically meaningful theoretical distinctions. However, the PCS (at least as presently constructed) fails to discriminate these distinctions. Joint efforts in theory and measurement science could illuminate the role that posited "kinds" of pain catastrophizing play in individuals' pain experiences.

Monte Carlo Modeling of Contemporary Intelligence Test (IQ) Factor Structure: Implications for IQ Assessment, Interpretation, and Theory.

Researchers continue to debate the constructs measured by commercial ability tests. Factor analytic investigations of these measures have been used to develop and refine widely adopted psychometric theories of intelligence particularly the Cattell-Horn-Carroll (CHC) model. Even so, this linkage may be problematic as many of these investigations examine a particular instrument in isolation and CHC model specification across tests and research teams has not been consistent. To address these concerns, the present study used Monte Carlo resampling to investigate the latent structure of four of the most widely used intelligence tests for children and adolescents. The results located the approximate existence of the publisher posited CHC theoretical group factors in the Differential Abilities Scales-Second edition and the Kaufman Assessment Battery for Children-Second edition but not in the Wechsler Intelligence Scale for Children-Fifth edition or the Woodcock-Johnson IV Tests of Cognitive Abilities. Instead, the results supported alternative conceptualizations from independent factor analytic research. Additionally, whereas a bifactor model produced superior fit indices in two instruments (Wechsler Intelligence Scale for Children-Fifth edition and Woodcock-Johnson IV Tests of Cognitive Abilities), a higher order structure was found to be superior in the Kaufman Assessment Battery for Children-Second edition and the Differential Abilities Scales-Second edition. Regardless of the model employed, the general factor captured a significant portion of each instrument's variance. Implications for IQ test assessment, interpretation, and theory are discussed.

Investigating the Theoretical Structure of the Differential Ability Scales—Second Edition Through Hierarchical Exploratory Factor Analysis

When the Differential Ability Scales–Second Edition (DAS-II) was developed, the instrument’s content, structure, and theoretical orientation were amended. Despite these changes, the Technical Handbook did not report results from exploratory factor analytic investigations, and confirmatory factor analyses were implemented using selected subtests across the normative age groups from the total battery. To address these omissions, the present study investigated the theoretical structure of the DAS-II using principal axis factoring followed by the Schmid–Leiman procedure with participants from the 5- to 8-year-old age range to determine the degree to which the DAS-II theoretical structure proposed in the Technical Handbook could be replicated. Unlike other age ranges investigated where at most 14 subtests were administered, the entire DAS-II battery was normed on participants aged 5 to 8 years, making it well suited to test the full instrument’s alignment with theory. Results suggested a six-factor solution that was essentially consistent with the Cattell–Horn–Carroll (CHC)-based theoretical structure suggested by the test publisher and simple structure was attained. The only exception involved two subtests (Picture Similarities and Early Number Concepts) that did not saliently load on a group factor. Implications for clinical practice are discussed.

Comparison of methods for factor extraction for cognitive test-like data: Which overfactor, which underfactor?

Research published in Intelligence showed that the number of factors measured by individual intelligence tests has increased dramatically over time (Frazier & Youngstrom, 2007). When “gold standard” methods (parallel analysis based on principal components analysis, PA-PCA, and minimum average partial, MAP) were applied to these same tests fewer factors emerged, leading the authors to conclude that tests were inappropriately overfactored, and that modern tests are measuring far fewer underlying constructs than they are intended to measure. The article was influential, with the findings cited commonly and used to guide subsequent analyses. Here, we tested a key assumption of Frazier and Youngstrom and subsequent research that has used these methods: whether MAP and PA-PCA are accurate in recovering the correct number of factors with cognitive-test-like data. MAP and PA-PCA were compared to other exploratory and confirmatory factor analytic techniques in their ability to recover the correct number of factors in simulated data. Data conformed to common values found in intelligence literature, and varied based on the number of tests per factor, magnitude of factor loadings and factor correlations, and sample size. Results showed that MAP and PA-PCA, in fact, underfactored under many realistic data conditions, meaning that they recovered too few factors. Confirmatory methods were more accurate. Among exploratory methods PA based on principal axis factoring (not principal components analysis) was most accurate, although all methods underfactored with few tests per factor and high factor correlations. These findings suggest that PA-PCA and MAP are not “gold standard” methods for determining the number of factors underlying intelligence data and that other methods are more accurate. We argue for the importance of formal and informal theory in factor analytic investigations of intelligence tests.

Mapping strengths into virtues: the relation of the 24 VIA-strengths to six ubiquitous virtues

The Values-in-Action-classification distinguishes six core virtues and 24 strengths. As the assignment of the strengths to the virtues was done on theoretical grounds it still needs empirical verification. As an alternative to factor analytic investigations the present study utilizes expert judgments. In a pilot study the conceptual overlap among five sources of knowledge (strength’s name including synonyms, short definitions, brief descriptions, longer theoretical elaborations, and item content) about a particular strength was examined. The results show that the five sources converged quite well, with the short definitions and the items being slightly different from the other. All strengths exceeded a cut-off value but the convergence was much better for some strengths (e.g., zest) than for others (e.g., perspective). In the main study 70 experts (from psychology, philosophy, theology, etc.) and 41 laypersons rated how prototypical the strengths are for each of the six virtues. The results showed that 10 were very good markers for their virtues, nine were good markers, four were acceptable markers, and only one strength failed to reach the cut-off score for its assigned virtue. However, strengths were often markers for two or even three virtues, and occasionally they marked the other virtue more strongly than the one they were assigned to. The virtue prototypicality ratings were slightly positively correlated with higher coefficients being found for justice and humanity. A factor analysis of the 24 strengths across the ratings yielded the six factors with an only slightly different composition of strengths and double loadings. It is proposed to adjust either the classification (by reassigning strengths and by allowing strengths to be subsumed under more than one virtue) or to change the definition of certain strengths so that they only exemplify one virtue. The results are discussed in the context of factor analytic attempts to verify the structural model.

Measuring Spirituality as Personal Belief in Supernatural Forces

Critical evaluations of commonly used spirituality measures find many wanting— with most lacking the properties required of scientific measures. Common deficiencies include using non-representative development samples, a failure to satisfy normality assumptions, and the confounding of related yet-distinct constructs (e.g. religiosity, wellbeing, civility, prosociality, virtues, etc). The current paper utilizes two studies to examine the psychometric properties of the 7-item Character Strength Inventory-Spirituality (CSI-Spirit; Isaacowitz, Seligman and Valiant 2003). Factor analytic investigations (exploratory and confirmatory) suggest that six items reliably (Cronbach’s a > .70) capture a single latent construct that accounts for around 45% of the variance in responses. This truncated CSI-Spirit appears normally distributed and uni-dimensional. Item difficulty (as reflected by mean scores on items) varies and total scores converge meaningfully with religious affiliation and measures of religiosity, spirituality, paranormal beliefs, wellbeing, agreeableness and conscientiousness. In summary, the CSI-Spirit appears statistically robust and its brevity makes it ideal for individual assessment (in psychological practice) and large scale socioepidemiological research purposes.

Relation Between Treatment Satisfaction and Treatment Outcome in Veterans with Posttraumatic Stress Disorder

Existing measures of patient treatment satisfaction are largely characterized by a lack of psychometric evaluation, varied definitions across studies, and small numbers of items. The present study evaluated a patient treatment satisfaction questionnaire specifically designed for psychiatric outpatient treatment satisfaction, the Charleston Psychiatric Outpatient Satisfaction Scale (CPOSS), to extend previous findings by examining: 1) the psychometric properties of the CPOSS and the common domains within patient treatment satisfaction, and 2) the preliminary relations between the CPOSS and treatment outcome during exposure therapy in patients with posttraumatic stress disorder (PTSD). The present investigation included two studies. The first involved 170 combat veterans with PTSD who completed brief psychotherapy, and whose post-treatment CPOSS scores were used for the factor analytic investigations. The second study involved 63 combat veterans with PTSD who received a course of brief exposure-based psychotherapy and completed pre- and post-treatment assessments to investigate the relations between the CPOSS and treatment outcome. The first study supported the psychometric properties of the CPOSS, including identifying four psychometrically-sound subscales for: respectful care, appearance of facility, convenience of facility, and recommendation to friends/family. The second study demonstrated that the CPOSS was a significant predictor of post-treatment PTSD symptoms, relative to demographics and pre-treatment symptoms. Together, these findings support the use of the CPOSS as a valuable addition in psychiatric outpatient settings to both assess and potentially improve patient treatment satisfaction.

Approach temperament, anger, and evaluation: Resolving a paradox.

Factor analytic investigations into the structure of naturalistically observed self-reported mood suggest that anger loads together with avoidance temperament markers, such as fear and anxiety. However, when anger is examined following experimental manipulation, it appears to relate more to approach temperament markers, such as determined and active. We explored 1 potential reason why there is a discrepancy between naturalistically collected self-reported mood versus experimental manipulation of affect with regard to the location of anger in the mood space. We propose that evaluation--endorsing items of similar valence regardless of their semantic content--confounds the self-reported structure of mood. The evaluative dimension of self-reported mood does not appear to represent actual behavior, because it combines items with contradictory semantic content as long as they have similar valence. For example, someone with a positive self-view may endorse both calm and excited while denying sluggish and manic, and so forth, even though these items describe opposite traits. Isolating evaluation across 4 inventories and samples showed that anger clustered together with approach temperament markers. We conclude that isolating evaluation generates a self-reported structure of mood that aligns more closely with experimental investigations.

Revaluating the evidence for the General Factor of Personality in the Multidimensional Personality Questionnaire: Concerns about Rushton and Irwing (2009)

We evaluated whether the Big Five-based hierarchical model for the Multidimensional Personality Questionnaire (MPQ) reported by Rushton and Irwing (2009) would replicate in a second sample of 733 participants. We were unable to confirm their hierarchical model and detected problems with the reporting of the original results. Exploratory factor analytic investigations generally supported the canonical three factor solution for the MPQ described in the existing literature. This was the case for both the present dataset and for the correlation matrix analyzed by Rushton and Irwing.

A (Re)-Evaluation of the Symptom Structure of Borderline Personality Disorder

Despite evidence of significant symptom heterogeneity and excessive diagnostic comorbidity, many contend that borderline personality disorder (BPD) is unidimensional, an assumption that rests primarily on results from factor analytic investigations of BPD symptom criteria. We note several limitations in the literature and argue that the symptom structure of BPD can be best clarified by using both factor analytic techniques and examining the BPD symptom dimensions in relation to external criteria (that is, personality traits). Our goals were to: examine if the symptoms of BPD are best conceptualized as unidimensional or multidimensional, and determine the extent to which personality traits account for any symptom dimensions that underlie BPD. All published structural models of the BPD symptom criteria were identified and tested for statistical fit using confirmatory factor analysis in a sample of 373 patients who had completed the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders-Axis II Personality Questionnaire BPD scale. Dimensions from the best fitting model were examined in relation to traits from the Five-Factor Model (FFM) and the Personality Psychopathology Five (PSY-5) using correlational and regression analyses. Sanislow's 3-factor model, containing affect dysregulation, behavioural dysregulation, and disturbed relations symptom dimensions, provided the best fit; the unidimensional model produced the worst. The symptom dimensions of the 3-factor model were differentiable from one another and had unique associations with the FFM and PSY-5 personality traits. BPD is a multidimensional construct.

The structure of feared social situations among individuals with a lifetime diagnosis of social anxiety disorder in two independent nationally representative mental health surveys

The present study employed both exploratory and confirmatory factor analytic approaches with nationally representative samples of individuals with a lifetime diagnosis of social anxiety disorder ( n=1123; n=3091, respectively) using split-halves of the National Comorbidity Replication Survey ( n=9282) and cross-validated with the Canadian Community Health Survey on Mental Health and Wellbeing ( n=36,984). Strong support was found for a three-factor solution. This model was obtained from exploratory factor analysis and was further evaluated using two confirmatory factor analytic investigations in the two national samples. The three social situational domains reflected (1) Social Interaction Fears, (2) Observation Fears, and (3) Public Speaking Fears. Individuals with generalized social anxiety disorder (i.e., those who endorsed 7 or more of 13 feared social situations assessed in the survey) were significantly more likely to report Social Interaction Fears and Observation Fears compared to individuals with non-generalized social anxiety disorder (i.e., those who endorsed only 6 or fewer of 13 feared social situations). Individuals with generalized social anxiety were particularly characterized by combinations of Public Speaking Fears plus Social Interaction Fears and Observation Fears. The clinical and classification implications of our study for DSM-V are discussed.

Replicability and stability of the multidimensional model of the Edinburgh Postnatal Depression Scale in late pregnancy

The Edinburgh Postnatal Depression Scale (EPDS) is a widely used screening tool for post-natal depression (PND). Recent factor analytic investigations of the EPDS have suggested the instrument may be useful in the prediction of PND as the instrument appears to be multidimensional, thus facilitating sub-scale development for this purpose. The psychometric properties of the EPDS were evaluated in women in the third trimester of pregnancy. Confirmatory factor analyses found support for the multidimensionality of the instrument; however, there was clear variability in model fit to data suggesting previous reports of the stability of the underlying factor structure of this instrument may be over-optimistic. The potential for development of the EPDS as a predictive screening measure of PND is likely to be optimistic because of variability in the factor structure of the instrument over the course of pregnancy and in the post-natal period.

Distinguishing the cognitive and behavioral consequences of attitude importance and certainty: A new approach to testing the common-factor hypothesis

Some published factor analyses have suggested that attitude importance and certainty are distinct psychological constructs, but other factor analytic investigations have suggested they are largely redundant reflections of a more general underlying construct. This latter sort of finding has led investigators to average measures of importance and certainty together into a composite index and then explore its cognitive and behavioral consequences. In this paper, we report three studies gauging the underlying structure of these strength-related attitude attributes by assessing whether they in fact relate in the same ways to information processing and action tendencies. We found that importance and certainty both independently predicted the likelihood that a person attempted to persuade others to adopt his or her attitude. Importance (but not certainty) was associated with the tendency to seek out information that would enable people to use their attitudes in a subsequent judgment and only importance predicted whether or not they turned out to vote in an election to express their attitudes. Certainty (but not importance) was related to the tendency to find more than one political candidate acceptable. And importance and certainty interacted to predict the frequency with which people performed attitude-expressive behaviors. All this suggests that importance and certainty have distinct effects on thinking and behavior and supports the maintenance of conceptual and empirical distinctions between them in social psychological theory building.

Post-Traumatic Stress Disorder Symptoms in United Nations Peacekeepers: An Examination of Factor Structure in Peacekeepers with and without Chronic Pain

Recent factor analytic investigations of post-traumatic stress disorder in military veterans suggest that symptoms are best described by either a hierarchical 2-factor model or a 4-factor inter-correlated model. Other recent evidence suggests that post-traumatic stress disorder and chronic pain are intricately related; however, the nature of this relationship is not well understood. Factor analysis provides one method for clarifying this relationship. In study 1, we compared competing models of post-traumatic stress disorder symptom structure in a sample of 400 male United Nations peacekeepers using confirmatory factor analysis. Results indicated that both the hierarchical 2-factor and the 4-factor inter-correlated models provided good fit to the data. In study 2, the reliability of these models was assessed in 427 male United Nations peacekeepers with chronic back pain and 341 without. Group comparisons of the confirmatory factor analysis results revealed that the structure of the hierarchical 2-factor and 4-factor inter-correlated models both provided good fit to the data in both the chronic back pain and the group without. However, the structure of the models for the group with chronic back pain group differed in significant ways from that of the group without chronic back pain. Post-traumatic stress disorder symptoms in military veterans can be adequately conceptualized using either a hierarchical 2-factor or 4-factor inter-correlated model. Chronic pain has a minimal influence on overall factor structure. The hierarchical 2-factor model, while parsimonious, does not provide the degree of symptom detail provided by the 4-factor inter-correlated model. Implications for conceptualization of post-traumatic stress disorder symptoms for patients with chronic back pain and significant post-traumatic stress disorder symptomatology are discussed.

Dimensionality of posttraumatic stress symptoms: a confirmatory factor analysis of DSM-IV symptom clusters and other symptom models

Recent exploratory [ Taylor, S., Kuch, K., Koch, W. J., Crockett, D. J., & Passey, G. (1998). The structure of posttraumatic stress symptons. Journal of Abnormal Psychology, 107, 154–160 .] and confirmatory [ Buckley, T. C., Blanchard, E. B., & Hickling, E. J. (1998). A confirmatory factor analysis of posttraumatic stress symptons. Behaviour Research and Therapy, 36, 1091–1099; King, D. W., Leskin, G. A., King, L. A., & Weathers, F. W. (1998). Confirmatory factor analysis of the clinician-administered PTSD scale: evidence for the dimensionality of posttraumatic stress disorder. Psychological Assessment, 10, 90–96. ] factor analytic investigations suggest that the three symptom clusters of posttraumatic stress disorder (PTSD) as defined in the Diagnostic and Statistical Manual [4th ed.; DSM-IV; American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author. ] may not provide the best conceptualization of symptom dimensionality. However, the alternative models have not been in agreement, nor have they been compared against each other or models based on the DSM-IV. The purpose of the present investigation was to test a series of dimensional models suggested by these recent factor analytic investigations and the DSM-IV. Using data collected with the PTSD Checklist—Civilian Version [ Weathers, F. W., Litz, B. T., Huska, J. A., & Keane, T. M. (1994). PCL-C for DSM-IV. Boston: National Center for PTSD—Behavioral Science Division. ] from 349 referrals to a primary care medical clinic, we used confirmatory factor analysis to evaluate a: (1) hierarchical four-factor model, (2) four-factor intercorrelated model, (3) hierarchical three-factor model, (4) three-factor intercorrelated model, and (5) hierarchical two-factor model. The hierarchical four-factor model (comprising four first-order factors corresponding to reexperiencing, avoidance, numbing, and hyperarousal all subsumed by a higher-order general factor) provided the best overall fit to the data; although, all models met some standards specified for good model fit. More research is needed to establish the dimensional nature of PTSD symptoms and to assess whether identified dimensions differ as a function of the trauma experience. Implications for assessment, diagnosis, and treatment are also discussed.

Illness Attitudes Scale dimensions and their associations with anxiety-related constructs in a nonclinical sample

The Illness Attitudes Scale (IAS) is a self-rated measure that consists of nine subscales designed to assess fears, attitudes and beliefs associated with hypochondriacal concerns and abnormal illness behavior [Kellner, R. (1986). Somatization and hypochondriasis. New York: Praeger; Kellner, R. (1987). Abridged manual of the Illness Attitudes Scale. Department of Psychiatry, School of Medicine, University of New Mexico]. The purposes of the present study were to explore the hierarchical factor structure of the IAS in a nonclinical sample of young adult volunteers and to examine the relations of each illness attitudes dimension to a set of anxiety-related measures. One-hundred and ninety-seven undergraduate university students (156 F, 41 M; mean age=21.9 years) completed the IAS as well as measures of anxiety sensitivity, trait anxiety and panic attack history. The results of principal components analyses with oblique (Oblimin) rotation suggested that the IAS is best conceptualized as a four-factor measure at the lower order level (with lower-order dimensions tapping illness-related Fears, Behavior, Beliefs and Effects, respectively), and a unifactorial measure at the higher-order level (i.e. higher-order dimension tapping General Hypochondriacal Concerns). The factor structure overlapped to some degree with the scoring of the IAS proposed by Kellner (1986, 1987), as well as with the factor structures identified in previously-tested clinical and nonclinical samples [Ferguson, E. & Daniel, E. (1995). The Illness Attitudes Scale (IAS): a psychometric evaluation on a nonclinical population. Personality and Individual Differences, 18, 463–469; Hadjistavropoulos, H. D. & Asmundson, G. J. G. (1998). Factor analytic investigation of the Illness Attitudes Scale in a chronic pain sample. Behaviour Research and Therapy, 36, 1185–1195; Hadjistavropoulos, H. D., Frombach, I. & Asmundson, G. J. G. (in press). Exploratory and confirmatory factor analytic investigations of the Illness Attitudes Scale in a nonclinical sample. Behaviour Research and Therapy; Speckens, A. E., Spinhoven, P., Sloekers, P. P. A., Bolk, J. H. & van Hemert, A. M. (1996). A validation study of the Whitley Index, the Illness Attitude Scales and the Somatosensory Amplification Scale in general medical and general practice patients. Journal of Psychosomatic Research, 40, 95–104]. The Fears, Beliefs and Effects lower-order factors and the General Hypochondriacal Concerns higher-order factor, were shown to be strongly associated with anxiety sensitivity, even after accounting for trait anxiety and panic history. Implications for understanding the high degree of comorbidity between the diagnoses of panic disorder and hypochondriasis, as well as future research directions for exploring the utility of various IAS dimensions in predicting responses to lab-based bodily symptom-induction procedures, are discussed.

Exploratory and confirmatory factor analytic investigations of the Illness Attitudes Scale in a nonclinical sample

The Illness Attitudes Scale (IAS) assesses fears, beliefs and attitudes associated with hypochondriasis [Kellner, R. (1986). Somatization and hypochondriasis. New York: Praeger Publishers.]. Recent factor analytic investigations of the IAS in non-clinical samples have suggested a number of different factor solutions. In study 1, we used principal components analysis with both orthogonal and oblique rotation to better explore the structure of this measure. Using a random selection of 390 participants from a larger pool of 780, a five-factor solution was identified: (1) fear of illness, death, disease and pain, (2) effects of symptoms, (3) treatment experiences, (4) disease conviction and (5) health habits. In study 2, confirmatory factor analysis (CFA) of responses from the remaining 390 students evaluated: (a) a single-factor model, (b) Kellner's original nine-factor model, (c) a four-factor model proposed by Ferguson and Daniel [Ferguson, E. & Daniel, E. (1995). The Illness Attitudes Scale (IAS): a psychometric evaluation on a nonclinical population. Personality and Individual Differences, 18, 463–469.], (d) a different four-factor model proposed by Stewart and Watt [Stewart, S. H. & Watt, M. C. (1998). A psychometric investigation of the Illness Attitudes Scale (IAS) in a nonclinical young adult sample. Submitted for publication.] and (e) the five-factor model derived in study 1. Of these models, greatest support was obtained for our five-factor model. However, it was also clear that this model could be improved. Based on the results of the CFA, as well as previous research and theoretical considerations, we tested a revised model in which the health habits factor was deleted. Analysis of the revised model showed that it received the greatest support and could be conceptualized as either four distinct factors or as hierarchical in nature, with four lower-order factors loading on a single higher-order factor. Future directions for research as well as suggestions for scoring and using the IAS with nonclinical samples are discussed.

Developing a Performance Management Audit Questionnaire

In this study the authors aim to develop and validate a Performance Management audit questionnaire. The audit questionnaire, consisting of 102 items, was completed by 626 South African managers and employees from eight organizations representing finance, commerce, industry and utility organizations. Items for the audit questionnaire, which was developed specifically for this study, were obtained from interviews with Performance Management facilitators, related literature and results from a survey on problems experienced with Performance Management. Items were categorized according to a systems model of Performance Management. Results from an item analysis and a series of factor analytic investigations provide limited confirmation that the Performance Management Audit Questionnaire (PMAQ) provides a reliable and content valid measure of the Performance Management domain as conceptualized by the systems model. Three second-order factors were identified, i.e. management processes, feedback, and linkages at various levels. Performance Management seems to emerge as a considerable force in both conceptually and operationally integrating various human resources related activities.

Dimensions of personality disorder and their relationships to the Big Five dimensions of personality.

Researchers have suggested that personality disorders (PDs) could be better understood with a dimensional model than with the DSM-IIII-R categorical system. The authors conceptualized PDs as extreme expressions of personality functioning. Dimensional measures of aspects of PD were developed for the present study on the basis of previous factor-analytic investigations. The authors examined the convergence of these measures with Costa and McCrae's «Big Five» factors in a sample of 300 general-population subjects

Subjective assessment of sleep by Sleep Questionnaire.

A 55-item Sleep Questionnaire is presented for possible use as a standardized instrument in psychological studies of sleep. A factor analysis of responses from 145 adults to the questionnaire indicated 7 factors accounted for 71.7% of the total variance. These factors are congruent with sleep dimensions discussed in the literature and with other factor analytic investigations. A set of 11 clinical judgment scales are also presented. The reliabilities of both factor and clinical scales are adequate as judged by test-retest, internal consistency, and comparisons of self vs spouse ratings. The construct validity is supported by three studies showing significant differences between (a) medical patients with and without sleep disturbances, (b) psychiatric patients with and without symptoms of depression, and (c) short and long sleepers.