Can a test be reliable without being valid?

A test can indeed be reliable without being valid. Reliability refers to the consistency of a test's results over time or across different instances. If a test yields the same results under consistent conditions, it demonstrates reliability. For example, a test measuring someone's height using a faulty measuring tape can still yield the same height measurement repeatedly, indicating reliability.

However, validity assesses whether a test actually measures what it claims to measure. If a test is reliable but consistently measures something irrelevant to the intended construct, it lacks validity. For instance, a reliable test that consistently measures shoe size will not be valid if the intent is to measure intelligence.

This distinction illustrates that a test can consistently produce the same results (reliability) while failing to assess the intended attribute accurately (validity). Hence, the assertion that a test can be reliable without being valid is substantiated by these principles of measurement theory.