prec_meandiff: Sample size or precision for a mean difference

In a-lenz/presize: Precision Based Sample Size Calculation

Description

prec_meandiff returns the sample size or the precision for the provided mean difference and standard deviations

Usage

prec_meandiff(delta, sd1, sd2 = sd1, n1 = NULL, r = 1,
  conf.width = NULL, conf.level = 0.95, variance = c("equal",
  "unequal"), tol = .Machine$double.eps^0.25)

Arguments

delta	difference in means between the two groups.
sd1	standard deviation in group 1.
sd2	standard deviation in group 2.
n1	Number of patients in unexposed group
r	allocation ratio (relative size of unexposed and exposed cohort (n1 / n2))
conf.width	precision (the full width of the conficende interval)
conf.level	confidence level
variance	equal (default) or unequal variance.
tol	numerical tolerance used in root finding, the default providing (at least) four significant digits

Details

Exactly one of the parameters n, conf.width must be passed as NULL, and that parameter is determined from the other.

Value

Object of class "presize", a list of arguments (including the computed one) augmented with method and note elements.

Examples

prec_meandiff(delta = 5, sd1 = 2.5, n1 = 20, var = "equal")
prec_meandiff(delta = 5, sd1 = 2.5, conf.width = 3, var = "equal")

a-lenz/presize documentation built on May 17, 2019, 7:44 a.m.