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Methods Inf Med 1993; 32(04): 314-316
DOI: 10.1055/s-0038-1634942
Original Article
Schattauer GmbH

Stratified Initial Values and Change Scores

P. A. Lachenbruch
1   UCLA School of Public Health, Los Angeles Cal., USA
,
T. W. Wilson
2   Human Population Laboratory, Western Consortium for Public Health, Los Angeles Cal., USA
,
R. D. Cohen
3   Human Population Laboratory, California Public Health Foundation, Los Angeles Cal., USA
› Author Affiliations
Further Information

Publication History

Publication Date:
06 February 2018 (online)

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Abstract

A common question that is encountered in many studies is relating a change in a variable to the variable’s initial value. It is well known that regressing the change on the initial value creates a spurious association and misleads the unwary. One attempt to cope with this problem has been to stratify that data based on the initial value. We show that this approach does not solve the problem. Theoretical and simulation results for independent normal and independent exponential random variables are provided.

Key-Words

Stratification - Change Score - Initial Value
 

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