Personality Assessment Inventory
Personality Assessment Inventory (PAI), authored by Leslie Morey, PhD, is a multi-scale test of psychological functioning that assesses constructs relevant to personality and psychopathology evaluation (e.g., depression, anxiety, aggression) in various contexts including psychotherapy, crisis/evaluation, forensic, personnel selection, pain/medical, and child custody assessment. The PAI has 22 non-overlapping scales, providing a comprehensive overview of psychopathology in adults. The PAI contains four kinds of scales: 1) validity scales, which measure the respondent's approach to the test, including faking good or bad, exaggeration, or defensiveness; 2) clinical scales, which correspond to psychiatric diagnostic categories; 3) treatment consideration scales, which assess factors that may relate to treatment of clinical disorders or other risk factors but which are not captured in psychiatric diagnoses (e.g., suicidal ideation); and 4) interpersonal scales, which provide indicators of interpersonal dimensions of personality functioning.
The rationale behind the development of the PAI was to create an assessment tool that would enable the measurement of psychological concepts while maintaining statistical strength. The development methodology was based on several advances that the field of personality assessment was witnessing at the time. Due to the fuzzy nature of constructs (concepts) in psychology, it is very difficult to use criterion-referenced approaches, such as those used in some parts of medicine (e.g. pregnancy tests). This is why construct validation is very important to personality test development. It is usually described as being involved when tests intend to measure some construct that is not "operationally defined." The PAI was developed because the authors of the instrument felt that there were a limited number of self-report questionnaires that were using this type of construct validation method to assess areas relevant to diagnoses and treatment planning.
The developers of the PAI examined various literary sources to come up with the five areas assessed by the PAI (validity of responses, clinical symptoms, interpersonal styles, complications for treatment, and characteristics of one’s environment). Constructs were included if they had been relatively stable in their importance of diagnosing mental disorders over time, and if they were important in contemporary clinical practice. The construct validation approach that was used to construct the PAI was used to maximize two types of validity: content validity and discriminative validity. To ensure that the PAI maximized content validity, each scale had a balanced sample of items that represented a range of important items for each construct. For example, the Depression scale has items involving physical, emotional, and cognitive content (as opposed to only questions about mood or interests). Each scale also assesses a range of severity for that scale; for example, the Suicidal Ideation scale has items that range from vague ideas about suicide to distinct plans for self-harm. To ensure that the PAI maximized discriminant validity, each of the scales should be relatively distinct from one another. For example, if the depression and anxiety scales had many of the same items on them, it would be difficult to tell if elevations on these scales meant that the person was experiencing symptoms of depression, anxiety, or both. As such, the developers of the PAI stressed the fact that their measure has no overlapping items to ensure better interpretation of the scales. 
The developers of the PAI commend their method because it focuses on the content of psychological concepts. The initial items were written so that the content would be directly relevant to the different constructs measured by the test. These items were rated for their quality, appropriateness, and bias. For example, a bias review panel identified items that could seem to be pathological but are actually normal within a subculture. After ensuring that the PAI addressed certain concepts in psychopathology, the developers proceeded to a second stage in the process. This stage involved the "empirical evaluation" of the items. The research team administered two versions of the test, first to a sample of college students and later to a normative sample. These versions were evaluated using several criteria, such as internal consistency of the scales (or how much the items in one scale correlate with each other). The ability to fake good or bad while taking the test was also evaluated using a sample of college students that were given different instructions on how to answer the test.
The PAI contains four different types of scales: the validity scales are designed to measure how the person taking the inventory is responding. For example, the respondent may be marking items inconsistently, they may endorse symptoms that are unusual or bizarre, or they may attempt to create an overly positive or negative presentation of themselves. The validity scales are an attempt to quantify these response styles, and consist of the Inconsistency, Infrequency, Negative Impression, and Positive Impression scales. The Clinical scales assess features of 11 different clinical constructs that have been shown to be important in diagnosing psychological disorders, and include: Somatic Complains, Anxiety, Anxiety-Related Disorders, Depression, Mania, Paranoia, Schizophrenia, Borderline Features, Antisocial Features, Alcohol Problems, and Drug Problems. There are five Treatment Scales that are designed to measure factors that may potentially complicate treatment if the person was in therapy, and include: Aggression, Suicidal Ideation, Stress, Nonsupport, and Treatment Rejection. The treatment scales can be especially useful because these factors aren’t necessarily picked up by the Clinical Scales, but are still important when considering diagnoses and treatment options. There are two Interpersonal Scales: Dominance (the extent to which the respondent is either controlling or submissive in their relationships) and Warmth (the extent to which the respondent is empathic, as opposed to withdrawn and unengaged). 
The PAI is often used in forensics and corrections, where moderate support for its validity has been noted. The PAI has a number of strengths for applied psychological assessment. First, respondents are asked to rate their responses on a 4-point graduated scale, (false, somewhat true, mainly true, very true,) rather than a true/false scale. This contributes to greater scale reliability and validity, as it provides respondents with the opportunity to give nuanced ratings of themselves. Second, it is relatively economical, assessing most of the constructs that are widely considered important in clinical personality assessment with only 344 items. Third, nearly all of the PAI items are readable at the 4th grade level. Brevity and straightforward item wording reduce the administrative burden on respondents. Fourth, the responses from each individual's profile are compared to two large samples. The first sample consists of 1,000 people with similar demographic characteristics (e.g., age, gender, ethnicity) to the U.S. Census data. Comparison with this group is useful to detect and estimate the severity of clinical problems relative to the average person. The second sample consists of 1,246 psychiatric patients. Comparison with this group helps assess the severity of psychopathology among other patients.
All of the constructs measured by the PAI are commonly used by psychologists and are named in such a way that they can be readily understood. Unlimited-use interpretive software that was written by the test author is available from the publisher, as well as an adolescent version of the test, the Personality Assessment Inventory-Adolescent (PAI-A), developed for use with adolescents 12 to 18 years of age. This measure requires only fourth-grade reading level and takes only 45 minutes to complete. The PAI-A also has the advantage of assessing borderline features, which most other instruments used with adolescents do not include. The Personality Assessment Screener ) is a 22-item instrument that provides an index of the likelihood that an important clinical elevation would occur on the PAI. This screening tool can be used as an adjunct to the PAI in appropriate circumstances. Straightforward scale names combined with the interpretive and diagnostic hypotheses provided in the computer report limit the burden on the examiner.
Finally, there are also a number of psychometric (statistical) strengths of the PAI, importantly including content validity and discriminant validity (for a detailed review of the PAI and its validity, see.)
The PAI is a self-report instrument. Self-report is one of many methods for psychological assessment, and thus relies on the individual taking the assessment to answer honestly. The PAI does not measure some constructs that might be of concern in clinical assessment (e.g., eating disorders), it is often useful to supplement the PAI with other measures for this reason as well. Caution should be exercised in interpreting PAI data from non-English speakers or when administration breaks from the standardized (self-administration) process. Boyle and Lennon (1994) expressed concerns about the measure's reliability and construct validity in a study of 211 participants, including 30 individuals with alcoholism and 30 individuals with schizophrenia. PAI-A scales do not correspond directly with DSM categories.
- Morey, L.C. (2007). The Personality Assessment Inventory professional manual. Lutz, FL: Psychological Assessment Resources.
- Douglas, Kevin S.; Guy, Laura S.; Edens, John F.; Boer, Douglas P. and Hamilton, Jennine “The Personality Assessment Inventory as a Proxy for the Psychopathy Checklist Revised: Testing the Incremental Validity and Cross-Sample Robustness of the Antisocial Features Scale”. Assessment, Vol. 14, No. 3, September 2007, pp. 255-269.
- Blais, Mark A.; Baity, Matthew R. and Hopwood, Christopher J. “Clinical Applications of the Personality Assessment Inventory”. Routledge, Oct. 2011, 256 pp.
- Morey, L.C. (1997). The Personality Assessment Screener (professional manual: Lutz, FL: Psychological Assessment Resources.
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