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Estimating Total Test Reliability from Parts of Unequal Length

Author(s):
Horst, Paul
Publication Year:
1950
Report Number:
RB-50-34
Source:
ETS Research Bulletin
Document Type:
Report
Page Count:
6
Subject/Key Words:
Reliability Formulas, Test Length, Test Reliability

Abstract

The Spearman-Brown split-half formula has been used for estimating a test's reliability from the correlation between its two comparable halves. However, it may be easier to get part scores from parts that are unequal in length and it is still possible to estimate the reliability of the total test correlation between the two parts if we know what proportion of the whole test is taken up by each part. Many mathematical formulas are provided. (SGK).

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