| stratum {clusrank} | R Documentation |
This is a special function used in the context of formula used for Wilcoxon sum rank test for clustered data. It identifies the stratum id of observations, and is used on the right hand side of a formula.
stratum(x)
x |
A numeric variable of stratum id. |
THe function's only action is semantic, to mark a variable as the stratum indicator. If not supplied, will assume no stratification in the data.
clusWilcox.test.formula