QUANTILES: Stata module to categorize by quantiles

quantiles creates a new variable (newvar) that categorizes varname by its quantiles. It differs from xtile because the categories are defined by the ideal size of the quantile rather than by the cutpoints, therefore yielding less unequaly sized categories when the cutpoint value is frequent, when using weights or when the number of observations in the dataset is not a product of the number of quantiles. It may not work properly on small datasets or if calculated for small groups. If the number of observations in the dataset or group is small, tabulate newvar afterwards to check the results.