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Goodness of fit of binary logistic model

Thanks, Frank. The following piece of code generate data, which
exhibit the problem I reported:

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set.seed(123)
intercept = -1.32
beta = 1.36
xtest = rbinom(1000,1,0.5)
linpred = intercept + xtest*beta
prob = exp(linpred)/(1 + exp(linpred))
runis = runif(1000,0,1)
ytest = ifelse(runis < prob,1,0)
xtest <- as.factor(xtest)
ytest <- as.factor(ytest)
require(rms)
model <- lrm(ytest ~ xtest,x=T,y=T)
model
residuals.lrm(model,'gof')
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Paul
On Fri, Aug 5, 2011 at 7:58 PM, Frank Harrell <f.harrell at vanderbilt.edu> wrote: