Is PI reliable and valid?

“Validity” and “reliability” have very specific meanings in psychometrics, the branch of psychology that deals with testing and assessment. In plain English, "reliability" and "validity" are two approaches to judging the usefulness of a psychological measure like the Predictive Index.

Definition of Reliability:
Reliability refers to the consistency or stability of a measure. If the concept being measured is assumed to be consistent, such as a personality trait, then the measure should yield similar results if the same person responds to it a number of times.

If the concept being measured is assumed to be inconsistent, such as mood, then the measure should yield dissimilar results if a person completes it several times.

One way to estimate reliability is by computing the measure’s "test-retest reliability". This is accomplished by giving the same people the same measure at two different times and statistically comparing the two scores.

An independent study by Dr J Christopher Perry and Dr Philip W Lavori describes the excellent test-retest reliability of the PI, especially of the Self factors, as would be expected since these measure natural behaviors.

There are two general ways to compute internal consistency reliability, and the PI has impressively demonstrated such reliability using both methods. Split-half reliability was investigated in the Perry and Lavori study mentioned above, and Cronbach’s alpha was investigated in a study by Dr. Richard Wolman and James Pratt ("A Normative Reliability Investigation of the Predictive Index Organization Survey Checklist"). Both studies demonstrated that the Predictive Index possesses strong internal consistency reliability.

Definition of Validity:
While reliability refers to the consistency of a measure, validity refers to the accuracy of a measure. A measure is valid if it actually measures what it purports to measure. The Predictive Index clearly does.

Construct validity is demonstrated when a measure is statistically compared with another measure of similar and/or different concepts. To be successful, the comparison measure must have been soundly constructed and be generally accepted.

Such research has been successfully performed twice, in the Perry and Lavori study and in a more recent 1996 study by Wolman and Pratt ("The Construct Validity of Predictive Index and 16PF"). Both studies compared the PI to Cattell’s 16PF (a well-respected and well-researched tool, though not developed for use in business).

Criterion-related validity is demonstrated when a measure is statistically compared with behaviours it claims to predict. We say that the PI is related to, and can predict, behaviors in the workplace. Criterion-related validity studies objectively show whether these relationships exist, and when they do, the nature of these relationships.

Since 1972 the PI has been investigated in over 400 criterion-related validity studies, for a variety of jobs in a variety of industries. The PI has consistently been shown to be job-related.This body of evidence overwhelmingly demonstrates that the PI is related to job behaviors.

If you have additional questions about validity, please email This e-mail address is being protected from spambots. You need JavaScript enabled to view it of PI Worldwide.

Protection from Adverse Impact and PI

We have performed research to determine whether the Predictive Index discriminates against protected classes. In a report written by Dr. Wolman of Harvard University, the PI was analysed to determine whether men and women tended to score differently on the PI, and whether African-Americans, Hispanics, and Caucasians tended to score differently on the PI.  

Wolman’s analyses showed that neither gender nor race substantially affected PI scores. In a more recent study by Dr Todd Harris, the PI was analysed to determine whether the PI produces adverse impact based on age. The study showed that for all PI factors, people over age 40 (the protected class) had PI patterns that were no different than people under age 40, confirming similar findings initially obtained by Dr. Wendi Everton in 1998. The Predictive Index does not create an adverse impact on these protected classes.

Cross-Cultural Research on the PI

The PI truly is an international tool, as evidenced by our thousands of clients around the globe, as well as the PI’s availability in over 60 languages. For example, in 2006, approximately 30% of the company’s revenue was derived from non-US markets. Since the early 1970’s, PI Worldwide has employed an outside language consultancy to provide rigorous translations of the PI into an ever-expanding number of native languages.

We continue to take steps to insure the PI’s validity in non-US markets. For example, since 2003 we have conducted criterion-related validity studies involving employees from Canada, India, UK, Spain, Portugal, Germany, Australia and the Netherlands. The results of these international job validity efforts demonstrate the same strong quantitative connections between the PI and job performance that our US-based studies have shown.

Recent studies have also documented the PI’s internal consistency reliability, freedom from bias, and construct validity in non-US markets. For example, in 2000 and 2003 in studies of the Swedish version of the PI checklist, Dr. Lennart Sjoberg of the Stockholm School of Economics demonstrated that the PI had acceptable reliability, validity and internal factor structure.

The report “The Construct Validity of the Predictive Index in a South African Sample” (1996) demonstrated PI’s construct validity as compared to the well-regarded 16PF personality assessment. The 2006 report entitled “The Impact of Race and Gender on PI Scores in a Large South African Sample” indicated that PI scores were not significantly impacted by race or gender in 1 620 employees from South Africa.

What does the PI measure?

There are four primary and two resultant factors that make up the Predictive Index. The four primary factors are called Factor A, Factor B, Factor C, and Factor D; the resultant factors are referred to as Factor M and Factor E. Each describes basic drives and motivations that all humans have, and each is represented by a continuum of scores.

Factor A (Dominance) measures the drive to exert one’s influence over people and events. Factor B (Extroversion) measures the drive for social interaction with other people. Factor C (Patience) measures the intensity of a person’s pace. Factor D (Formality) measures the drive to conform to formal rules and structure.

Factor M is a measure of a person’s stamina. Factor E measures the extent to which the individual is either subjective or objective in his or her judgments and decision-making.

These factors are then investigated within the context of three elements: the Self, the Self-Concept, and the Synthesis.

The Self is a measure of an individual’s basic pattern of drives and behavior – a measure of those drives that are most motivating and those behaviours that are most natural for that individual.

The Self-Concept measures the environmental expectations or demands that a person feels, which may or may not fit with his or her natural tendencies.

The Synthesis, a mathematical combination of the Self and Self-Concept scores, is designed to measure how that person is actually behaving in the current environment.

Does the PI measure cognitive ability?

The PI is a behavioural assessment tool that does not measure cognitive ability. Although cognitive ability is an important aspect of the individual to consider for many jobs, it is inappropriate to use cognitive ability as a blanket selection tool for all jobs. For this reason, the publishers of the Predictive Index have opted to maintain the Predictive Index as a tool that can be safely and appropriately used universally.

What is the reading level of the PI? What if someone cannot read at that level?

The Predictive Index has an eighth-grade reading level. The reading level of an individual taking the PI should affect the PI in only one way (the M Factor), and in a way expected and predicted by the theory behind the PI.

The Predictive Index checklist may be understood as a symbolic environment composed of 172 varied, symbolic stimuli, responses to which provide information about behaviour and motivation in the real environment. If someone selects fewer words from the checklist, either due to not knowing what some words mean or thinking that those words do not describe him or her or what is expected of him or her, the person is simply reacting to the PI environment as he or she would react in the actual workplace environment. Furthermore, it is important to remember that the PI measures natural drives and behaviors – not education level, not intelligence, and not socio-economic status (see relevant FAQ answers).

What support is available to validate the PI’s relationship to performance for specific jobs?

For any and all of our clients, Praendex Inc., the publisher of the Predictive Index, will perform criterion-related validity studies free of charge. There is no limit to the number of studies that can be performed, though it is important that there must be a sufficient number of employees currently performing the job, and adequate measures of their job performance. These studies are performed by Todd Harris, Ph.D, the Director of Research of Praendex, who is happy to answer any questions about conducting these studies – though your PI Consultant is the first person with whom you should speak about validity studies.

What about the EEOC guidelines on the use of selection procedures – is the PI safe?

The United States government’s Equal Employment Opportunity Commission (EEOC) has published and vigorously upheld "Uniform Guidelines for Employee Selection Procedures." These guidelines, which all U.S. businesses are required to meet, address the conduct of criterion-related validity studies. They were designed to protect individuals from "protected classes" from discriminatory employment decisions based on arbitrary methods.

Because of these guidelines, many US employers are understandably wary of products that can help them make employment decisions, such as the PI. Our nearly 8 000 clients, however, are comforted by these facts:
1.    as demonstrated by our criterion-related validity studies, the PI’s results are not arbitrary;
2.    in over 50 years, no court has ever upheld a challenge on the use of the PI;
3.    at any time, as part of the service contract, a client can commission us to perform, free of charge, a criterion-related validity study that uses their own employees and performance measures.

What support will PI offer if we face litigation attacking our use of PI and its validity?

In response to challenges attacking the validity or reliability of Predictive Index, PI Worldwide will provide copies of its research reports on the validity and reliability of PI, and, if necessary, will provide access to its research staff to answer any questions or challenges.

What protection does the PI have on the issue of adverse impact?

We have performed research to determine whether the Predictive Index discriminates against protected classes.

In a study conducted by Harvard psychologist Dr. Wolman, the PI was analysed to determine whether men and women tended to score differently on the PI, and whether African-Americans, Hispanics, and Caucasians tended to score differently on the PI. The analyses showed that neither sex nor race affected PI scores.

In a more recent study by Dr. Wendi Everton, the PI was analysed to determine whether the PI produces adverse impact based on age. This study showed that for all PI factors, people over 40 (the protected class) had PI patterns that were no different than people younger than 40. In short, the Predictive Index does not have an adverse impact on these protected classes.

Is the PI a valid tool for management selection decisions and/or the development of managers?

The use of the PI with managers and executives has been a focus of both formal and informal study over many years. In terms of formal research, the studies mentioned above that investigated the PI’s general reliability and validity contained individuals from all levels within organisations, including managers.

Furthermore, our library of research now includes 414 criterion-related validity studies including approximately 100 for a variety of managerial positions, including sales managers, supermarket store managers, and restaurant managers. These studies unequivocally show that the PI is related to the performance of managers at all levels of organisations.

An example of our informal research is a comparison of the PI profiles of a sample of top executives in the early 1970’s and another sample gathered in 1999. Analyses showed that both groups exhibited the PI profile we would predict for top executives.

South African Validity

Predictive Index has been used with confidence by South African businesses since the 1970’s.

A validity report dated 2006.06.01 titled “The Impact of Gender and Race on Predictive Index® scores in a Large South African Sample” concluded: The results of this study clearly indicate that Predictive Index scores are neither a meaningful function of, nor influenced by gender or Race within South Africa.

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