Research Quarterly Abstracts |
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| Authors: | Franklin M Henry |
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| Institution: | University of California , Berkeley , California , USA |
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| Abstract: | Abstract Independent estimates of the errors of measurement and the intra-individual variations have been made for arm strength (Smedley dynamometer) and vertical jumping (Henry apparatus). The intra-individual variations are much larger than the measurement errors; thus they constitute the chief factor that determines test-retest reliability in these two physical performances. The tolerable error for measuring strength is ± 0.82 kg.; for jumping it is ± 0.5 in. In order to avoid loss of accuracy, it is necessary to read the dial or scale with approximately twice this precision. The method of computing test-retest reliability as the ratio of “true score” variance to total variance is found to underestimate the coefficient when the variability of test and retest scores differs by more than 15 percent. A formula for correcting this attenuation is presented. |
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