Binary Response, Three Potential Predictors, Independent Observations
In a hypothetical study, a sample of 500 subjects had three potential predictors measured: age, sex, and systolic blood pressure, and a diagnosis of a certain disease (present/absent) was made. There is assumed to be no interaction between age and blood pressure. The relationship between continuous variables and the probability of disease is smooth. The data are found in the attachments below. To read the dataset into R you can run save the
.rda
file to a temporary area, then
load('prob1.rda')
which will create a data frame
d
in your workspace (search position 1). Alternatively, you can load the file ready for analysis directly from the WWW using
loadURL('http://biostat.mc.vanderbilt.edu/twiki/pub/Main/Puzzler1/prob1.rda')
.
Find a model that fits these data reasonably well. A
smooth relationship means that the function relating either age or blood pressure to the probability of disease, holding the other predictors constant, has at least two orders of continuity, in other words, has no gaps or corners.
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FrankHarrell - 09 May 2004; Modified 17 May 2004