Premium
A Note on Interpretation of Formulas for the Reliability of Differences
Author(s) -
Zimmerman Donald W.
Publication year - 1994
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/j.1745-3984.1994.tb00439.x
Subject(s) - reliability (semiconductor) , correlation , interpretation (philosophy) , statistics , mathematics , function (biology) , identity (music) , psychology , computer science , physics , power (physics) , geometry , quantum mechanics , evolutionary biology , biology , programming language , acoustics
It is widely recognized that the reliability of a difference score depends on the reliabilities of the constituent scores and their intercorrelation. Authors often use a well‐known identity to express the reliability of a difference as a function of the reliabilities of the components, assuming that the intercorrelation remains constant. This approach is misleading, because the familiar formula is a composite function in which the correlation between components is a function of reliability. An alternative formula, containing the correlation between true scores instead of the correlation between observed scores, provides more useful information and yields values that are not quite as anomalous as the ones usually obtained