[R] When models and anova(model) disagree...
Rob James
aetiologic at gmail.com
Thu Jun 16 00:17:52 CEST 2011
I have a situation where the parameter estimates from lrm identify a
binary predictor variable ("X") as clearly non-significant (p>0.3), but
the ANOVA of that same model gives X a chi^2-df rank of > 200, and
adjudicates X and one interaction of X and a continuous measure as
highly significant. The N is massive and X has two categories, each
with > 100,000 observations. I would expect X to have a significant
impact on the outcome.
The full model includes a large number of continuous (coded with rcs
with 3 knots) and categorical variables, as well as a plethora of
interactions between the categorical and continuous variables. Only one
of the interactions between the binary variable and the other
categorical or continuous variables is statistically significant.
Can anyone offer a suggestion on what might explain this discordance?
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