Standard deviation

Usage

sd_value(dat, event_index, cell_index, subjectid_var, var, ...)

dat: data.table. The analysis data set.
event_index: vector of integers that index the rows in dat that match the definition of an 'event'. Matching is done via the INDEX_ column in dat.
cell_index: A vector of integers referencing the rows of dat (as specified by the INDEX_ column in dat) that match the population to be analyzed. See the "Endpoint Events" vignette in ramnog for more information.
subjectid_var: character. Name of the subject identifier variable in the data (default is "USUBJID").
var: Character. Name of the variable in the analysis data that is subject to the statistics.
...: Optional parameters.

A data.table containing the standard deviation.