Standard deviation

Usage

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

Arguments

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.

Value

A data.table containing the standard deviation.

Examples

dat <- data.table::data.table(
  USUBJID = c("S1", "S2", "S3"),
  AVAL    = c(1.5, 2.5, 3.5)
)
dat[, INDEX_ := .I]
#>    USUBJID  AVAL INDEX_
#>     <char> <num>  <int>
#> 1:      S1   1.5      1
#> 2:      S2   2.5      2
#> 3:      S3   3.5      3
data.table::setkey(dat, INDEX_)
sd_value(dat, event_index = dat[["INDEX_"]], cell_index = dat[["INDEX_"]],
         subjectid_var = "USUBJID", var = "AVAL")
#>     label        description qualifiers value
#>    <char>             <char>     <char> <num>
#> 1:     SD Standard deviation       AVAL     1