How Useful are Test Scores?

Test scores can be useful, but they require careful interpretation, keeping the purpose of the test in mind. A single test can only reflect a sample of skills; therefore, every score includes some degree of error in measurement-- no score is absolutely accurate. Scores are influenced by many factors, but particularly by the reliability and validity of the test. Reliable tests will yield consistent results if administered many times. Valid tests actually measure and predict what they are intended to measure. For example, a valid reading decoding (sounding out words) test will accurately distinguish students with strong and weak decoding skills; it will accurately predict which students will perform well in a phonics program and which students may have difficulty. We can place greater confidence in the scores provided by reliable and valid tests.

Many tests are of limited value when used with students who come from communities or cultures which are different from the White, middle class groups from which most scores are derived. Students who grow up in poor, rural or inner city communities, in ethnic minority families, or in families who primarily speak a language other than English are not typically well-represented in the standardization of tests, and scores obtained by these students may not reflect their true abilities.

Certain test scores are only useful for certain purposes, and not for others. Percentiles and standard scores, for example, are not intended to measure student growth. They only show relative standing compared to others, and this relationship does not necessarily change as students progress through school. Raw scores, such as words read correctly or number of multiplication problems solved correctly, can be plotted over time to reflect progress.

Instead of relying entirely on tests and scores, there are other types of information that can describe student performance. Test scores alone should never be the sole basis for making placement or other serious educational decisions, such as retention, promotion, graduation, or placement in special education. Teachers and other educators should use observations, school and health history, parent information, daily work samples, etc. in conjunction with tests. Usefulness of tests can also be enhanced when qualified assessment personnel such as school psychologists assist in the selection of tests and the interpretation of results.

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