alleryStart learning →Why can a z-score compare a score from one test with a score from a completely different test?
AIt removes each test's own scale
BIt uses the larger sample size
CIt counts only the top scores
DIt adds the two means together
Answer & Solution
Correct answer: A. It removes each test's own scale
1. Two tests can have different means and different standard deviations.
2. Raw scores from them are on different scales, so comparing them directly means nothing.
3. A z-score reports position in standard deviations from that test's own mean.
4. Once both scores are on that shared scale, the higher z-score marks the stronger result.
_Source: OpenStax High School Statistics (CC BY 4.0), section 6.1 The Standard Normal Distribution_
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