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Attributable risk and relative improvement over chance: A note on Copas & Loeber (1990)
Author(s) -
Nijsse M.
Publication year - 1992
Publication title -
british journal of mathematical and statistical psychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.157
H-Index - 51
eISSN - 2044-8317
pISSN - 0007-1102
DOI - 10.1111/j.2044-8317.1992.tb00996.x
Subject(s) - variance (accounting) , measure (data warehouse) , association (psychology) , mathematics , selection (genetic algorithm) , statistics , econometrics , economics , psychology , computer science , accounting , database , psychotherapist , artificial intelligence
Copas & Loeber's (1990) measure of association for 2times2 tables, relative improvement over chance (RIOC), is shown to be identical to Levin's measure of attributable risk. It is demonstrated that both measures are equal to the difference between the true positive rate and the false negative rate, standardized for the ratio of base rate and selection ratio. Also, it is shown that Copas & Loeber's formula for the variance of RIOC in large samples is identical to the formula for the variance of attributable risk in cross‐sectional research as developed by Walter (1976). Relationships between RIOC and some existing measures of association are mentioned. By using Copas & Loeber's numerical example, it is concluded that they rightly make a distinction between large and small samples.