Psychometric test reliability (2)

In this talk, you will learn about the importance of test reliability in psychometric assessments, the reasons why longer tests tend to be more reliable than shorter ones (up to the point of fatigue), and the different types of reliability such as internal consistency, test-retest, and parallel forms. You will also discover what reliability figures are considered acceptable and why controlling for error is essential to ensure a test’s validity in practice.

After this talk, you will:

• Understand why longer psychometric tests tend to be more reliable than shorter ones, up to the point of candidate fatigue.

• Know that reliability is crucial for a fair and accurate assessment of an individual.

• Be able to explain the importance of balancing test length to avoid fatigue while still gathering enough information.

• Recognise that reliability is a key requirement before considering validity in test selection.

• Be aware of sources of error in testing, including systematic error (within the test) and random error (from the environment or respondent).

• Understand the importance of controlling environmental and respondent factors to minimise random error.

• Know the different types of reliability: internal consistency, test-retest, and parallel forms.

• Be able to explain internal consistency and know why Cronbach’s alpha is used to measure it.

• Understand how test-retest reliability works and why it can be difficult to obtain.

• Recognise what parallel forms reliability is and when it is or isn’t expected in a test manual.

• Know the acceptable reliability coefficients for ability tests (0.8 and above) and personality assessments (0.7 and above).

• Understand why very high internal consistency may be a problem, especially for personality tests.

• Be able to evaluate reliability figures in test manuals and know what to do if they fall below desired levels.

• Appreciate the need to consider generalisability when looking at reliability results for different populations.