The value of standardized test scores is based on the ratio of correct to incorrect answers. So, for example, if all test-takers answer a particular question correctly or incorrectly, that question doesn’t have any value in comparing test-takers to each other. These tests are meaningful only if they present a comparison of individual scores to a norm group. For this reason, most of these tests also place scores in a percentile rank, indicating how that score compared to everyone else who took that particular administration of the test.
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