Final answer:
The correct answer to the question of which type of validity requires separate validation studies for different demographic subgroups is D. differential validity. Differential validity assesses a test's validity across various subgroups to ensure fairness and accuracy in measurements.
Step-by-step explanation:
The students are seeking clarification on which type of validity requires separate validation studies for different demographic subgroups. The correct answer to this question is D. differential validity. Differential validity occurs when a test has different levels of validity for different groups. To ensure that a psychological test is fair and accurately measures what it purports to for all demographic groups, separate validation studies are sometimes conducted for various subgroups. This is particularly important when the test is used in high-stakes situations such as employment selection, college admissions, or legal cases.
From the reference provided, another important aspect of testing is reliability, which indicates the consistency of a test's results. However, reliability is not sufficient on its own; a test must also be valid. A reliable test that is not valid does not measure what it is supposed to measure correctly. For example, construct validity concerns whether a test accurately measures the concept it is intended to measure. This is different from differential validity, which specifically relates to the validity of a test across different demographic groups.
Understanding different test validity types is crucial in experimental design and potentially for identifying lurking variables that could influence study results. Ensuring that tests are both reliable and valid across all groups is essential in producing trustworthy and fair outcomes in psychological research and assessments.