Thursday, December 17, 2009

Limitations of Test Scores

I found a hand-out from the National Association of School Psychologists entitled, "Using and Understanding Test Scores - A Hand-out for Teachers" by Andrea Canter, Minneapolis Schools and I wanted to share a part of it with you that explains the limitations of test scores:

"Scores can be useful, but must be interpreted carefully, 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. Score are influenced by many factors, but particularly by the reliability and validity of the test. Reliable tests will yield consistent results if administrered many times. Valid tests actually measure and predict what they are intended to measure. For example, a valid reading decoding 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 the scores were 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 often reflect some degree of bias.

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 the curriculum. Raw scores, such as words read correctlyor number of multiplication problems solved correctly, can be plotted over time to reflect progress.

Limitations of test scores can be minimized by using other types of information to describe student performance. Test scores alone should never be used to make placement or other serious educational decisions. Observations, school and health history, parent information, daily work samples, etc. should be used in conjunction with test scores.

Limitations of test scores can be further minimized by the use of qualified assessment personnel such as school psychologists to assist in the selection of tests and the interpretation of results."

The following texts provide an overview of assessment issues for educators, including test scores:
Hamill, D. (1987) Assessing the Abilities and Instructional Needs of Students. Austin, TX: Pro-Ed.
Salvia, J. & Ysseldyke, J. (1988) Assessment in Special and Remedial Education, 4th Edition. Boston: Houghton-Mifflin

I'll have another post at the beginning of next week that explains how test results should be reported to parents. J.T.

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