combined_sd {invivoPKfit}R Documentation

Combined standard deviation

Description

Given mean, standard deviation, and N for some set of groups, calculate the combined standard deviation. Note that the groups may not overlap.

Usage

combined_sd(
  group_mean,
  group_sd,
  group_n,
  unbiased = TRUE,
  na.rm = TRUE,
  log10 = FALSE
)

Arguments

group_mean

Numeric vector: Observed sample means for summary data, or observed values for non-summary data. Censored observations should *not* be NA; they should be substituted with some value at or below the corresponding LOQ (e.g. LOQ or LOQ/2). Even if 'log10 should *not* be log10-transformed.

group_sd

Numeric vector: Observed sample SDs for summary data. For non-summary data (individual-subject observations), the corresponding element of 'group_sd' should be set to 0. Even if 'log10 should *not* be log10-transformed.

group_n

Numeric vector: Observed sample number of subjects for summary data. For non-summary data (individual-subject observations), 'group_n' should be set to 1.

unbiased

Logical. If TRUE (the default), then 'group_sd' is assumed to be the unbiased estimator of population standard deviation (i.e. calculated using 'n-1' in the denominator – the way that 'stats::sd()' calculates it), and the returned combined SD is also the unbiased estimator of the combined population SD. If FALSE, then 'group_sd' is assumed to be the biased estimator (using 'n' in the denominator), and the returned value is also the biased estimator of the combined population SD.

na.rm

Logical. If TRUE (default), then any groups where mean, SD, *or* N were NA will be dropped. If FALSE, they will be retained (and the result will be NA).

log10

Logical. If TRUE, the standard deviations are from log10-transformed values.

Value

Numeric: the standard deviation of the combined population (i.e. if all the groups were concatenated into one large group).

Author(s)

Caroline Ring


[Package invivoPKfit version 2.0.1 Index]