Final answer:
A test without differential validity may still be valid for certain demographic groups but not others, highlighting the significance of both reliability and validity for accurate assessments.
Step-by-step explanation:
Without differential validity, a test may be valid for one demographic group but not for another. This means that while the test could accurately measure what it's intended to in one group, it may not do so across different groups. Differential validity is crucial for a test to be fair and equitable in its assessments across diverse populations.
Validity is a measure of the extent to which a test accurately measures what it's supposed to measure. For a test to be both normed and standardized, it has to be tested on a representative sample which ensures that its results are applicable to the broader population.
Thus, reliability alone does not guarantee a test's accuracy, as it has to be coupled with validity. For instance, a reliable test could consistently yield the same results (reliable), but those results might not measure the intended attribute accurately (valid).