What Are Psychometric Properties?

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The psychometric properties of a psychological test relate to the data that has been collected on the test to determine how well it measures the construct of interest.

In order to develop a good psychological test, the new test is subjected to statistical analyses to ensure that it has good psychometric properties.

There are two broad types of psychometric properties that a test must have in order to be considered a good measure of a particular construct, reliability, and validity.

Reliability as a Psychometric Property

The first type of psychometric property is called "reliability." This is the psychological test's ability to measure the construct of interest consistently and in a stable manner. A measure of something cannot be more valid than it is reliable.

Test-Retest Reliability

If the test is reliable, your results on that test should be very similar if you take the test today and again in six months. This is called test-retest reliability. 

For example, you take a test to determine your likelihood of having borderline personality disorder (BPD) in January, then again in July, and you should have similar results.

One problem with the reliability of testing the same person twice using the same test is that the patient could remember the questions from the last time they took the test. Which could have a variety of consequences?

Parallel Forms for Reliability

Parallel forms is another measure of reliability and designed to avoid the issues brought about by using the same exact test twice.


To increase the reliability of this psychometric property, clinicians administer parallel forms of a test. In other words, two similar, not exactly the same, versions of a measure.

Other Types of Reliability

There are other types of reliability. Internal consistency refers to the point that all the items in the test should be measuring the same construct.

Inter-rater reliability addresses the protocol to determine if multiple judges have a high degree of consensus. 

Validity as a Psychometric Property

The second broad property that a good test has is validity, which refers to how well the test accurately measures the construct of interest. The results should correspond with what the researcher stated was the focus of the study.

For example, the results of a good borderline personality test should be highly related to behavior that is typical of borderline personality disorder (for example, someone with a high score on a BPD test should also have a lot of problems with emotion regulation).

The two broad categories of validity are internal and external:

  • If the study has external validity, it falls in line with previous findings on the same, or similar, topic.
  • Internal validity is about the degree of confidence the researcher has in his own results and is based on a variety of factors, including characteristics of the sample, measures, and the research design.

    Face Validity

    Face validity refers to how valid the person taking the test thinks it is. For example, if the test taker has a bad attitude toward the test, including finding the layout confusing or the thinking the test administrator is a jerk, an otherwise valid measurement might produce an erroneous result. 

    Source: University of West Virginia: Research Psychometric Properties

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