Treatment of kidney stones
data(kstones)A data frame with 8 observations on the following 4 variables.
Countsthe number of subjects in the given classification; a numeric vector
Sizewhether the subject has kidney stones
with mean diameter less than 2cm (coded as Small)
or greater than or equal to 2cm (coded as Large);
a factor with levels Large and Small
Methodthe treatment method;
a factor with levels A (open surgery) or
B (percutaneous nephrolithotomy)
Outcomethe outcome of the stated treatment;
a factor with levels Failure and Success
The data give the success rates of two methods of treating kidney stones: open surgery methods, and percutaneous nephrolithotomy.
The given data are a subset of that reported by Charig et al. (1986), who also include two other methods of treatment, and also break up the open surgery methods into three sub-groups. The two methods here were chosen because they demonstrate Simpson's paradox.
data(kstones)
summary(kstones)
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