set.seed(1)
blood.pressure <- rnorm(200, 120, 15)
dd <- datadist(blood.pressure)
options(datadist='dd')
L <- .03*(blood.pressure-120)
sick <- ifelse(runif(200) <= plogis(L), 1, 0)
f <- lrm(sick ~ rcs(blood.pressure,5))
specs(f) # find out where 5 knots are placed
g <- Glm(sick ~ rcs(blood.pressure,5), family=binomial)
specs(g,long=TRUE)
options(datadist=NULL)
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