The data set PimaIndiansDiabetes2 contains a corrected
version of the original data set. While the UCI repository index
claims that there are no missing values, closer inspection of the data
shows several physical impossibilities, e.g., blood pressure or body
mass index of 0. In PimaIndiansDiabetes2, all zero values of
glucose, pressure, triceps, insulin and
mass have been set to NA, see also
Wahba+Gu+Wang:1995 and Ripley:1996.