The Basic Beliefs Behind Psychometric Testing

What are the Basic Beliefs Behind Psychometric Testing? - Selection by Design

What are the Basic Beliefs Behind Psychometric Testing? - Selection by Design

As providers of psychometric test training, we spend a good deal of time preparing persons to be skilled in administering, interpreting and making decisions based on psychological tests.

Occasionally we’re asked, how do we know that the testing process works? What are the basic beliefs, or what is the reasoning, behind psychometric testing?

As suggested by Reynolds and Livingston (2012), the use of psychometric tests in decision making is based on a number of assumptions. These are listed below, along with some implications worth considering.

  1. Psychological constructs exist

This is a basic, but important point. How do we know attributes like numerical ability, conscientiousness, or integrity exist? Psychometricians and researchers work diligently to put together evidence of construct validity to try to establish this.

  1. Psychological constructs can be measured

In other words, it’s assumed that a test or assessment can access and measure “how much” of an attribute exists.

  1. Although we can measure constructs, our measurement is not perfect

This raises the question of how much confidence we can have that any given test is a good measure of what we are interested in. Reliability is an important consideration here.

  1. There are different ways to measure any given construct

This is one reason why there can be so many different, yet equally effective tests on the market today. It’s also why we use different forms of measurement aside from traditional testing. For example, interviews, observed behaviour, and reports from superiors or peers can be taken into account in evaluating a candidate’s traits or abilities.

  1. All assessment procedures have strengths and limitations

This leads to key considerations when choosing a method of assessment. An important component of psychometric testing skills is the ability to evaluate and compare qualities of tests, such as evidence for reliability and validity, comparison groups (“norm groups”) available, practical considerations such as methods of administration, security, cost and time requirements.

  1. Multiple sources of information should be part of the assessment process

This assumption highlights the need to question and verify any information gathered during testing. For example, oral feedback interviews can verify traits suggested by written personality tests. Past records of performance can supplement ability test scores.

  1. Performance on tests can be generalized to non-test behaviour

Test scores themselves are less important than the implications we can draw from those scores about what an individual is likely to do in a specific situation. For example, a person who scores highly on conscientiousness could be expected to work carefully, with attention to detail.

But remember…behaviours are complex! In any situation, a person’s actions are the result of a vast number of attitudes, abilities, traits, beliefs, motives and thoughts. Scores from a test that could even perfectly measure any single attribute would only partly explain behaviour.

  1. Assessment can provide information that helps psychologists make better professional decisions

As opposed to intuition, assumptions or personal beliefs, testing offers a chance to objectively obtain information about individuals.

  1. Assessments can be conducted in a fair manner

Fair testing allows persons to be differentiated only according to level of attribute. Tests should not yield different scores based on demographic characteristics, including gender, race, age or other protected group status. Standardized testing procedures help to ensure fair opportunities for those being testing.

  1. Testing and assessment can benefit individuals and society as a whole.

In work related applications, psychometric testing can help ensure that persons are well matched in ability, talent, interest and personality to occupations and work activities. But tests have broader applications, in contexts including clinical and forensic assessment, education and individual self-development. By offering the opportunity for objective, fair and quantifiable assessment, tests help in making decisions that have far-reaching impact on both individuals and on society.



Reynolds, CR & Livingston, RB (2012). Mastering modern psychological testing: Theory & methods. New Jersey: Pearson Education, Inc.

Have questions about the assumptions behind psychometric testing? Contact us, or leave a comment below!


Ready to learn more about psychometric testing, or to become qualified in psychometric test use? Consider taking our next Test User Occupational training course(s). Find all the details here.

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