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Simpson's Paradox in Survival Models
Author(s) -
DI SERIO CLELIA,
RINOTT YOSEF,
SCARSINI MARCO
Publication year - 2009
Publication title -
scandinavian journal of statistics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.359
H-Index - 65
eISSN - 1467-9469
pISSN - 0303-6898
DOI - 10.1111/j.1467-9469.2008.00637.x
Subject(s) - covariate , context (archaeology) , mathematics , econometrics , outcome (game theory) , value (mathematics) , variable (mathematics) , event (particle physics) , statistics , mathematical economics , history , mathematical analysis , physics , archaeology , quantum mechanics
. In the context of survival analysis it is possible that increasing the value of a covariate X has a beneficial effect on a failure time, but this effect is reversed when conditioning on any possible value of another covariate Y . When studying causal effects and influence of covariates on a failure time, this state of affairs appears paradoxical and raises questions about the real effect of X . Situations of this kind may be seen as a version of Simpson's paradox. In this paper, we study this phenomenon in terms of the linear transformation model. The introduction of a time variable makes the paradox more interesting and intricate: it may hold conditionally on a certain survival time, i.e. on an event of the type { T > t } for some but not all t , and it may hold only for some range of survival times.