n_ttest: Sample Size Calculation for the two-sided t-Test

In goseberg/samplesizr: Sample-size calculation made simple

Description

n_ttest performs the Sample Size calculation for the t-Test to the level α comparing two independent samples. The method is based on the pages 16 - 18 in [1].

Null Hypothesis:

μ_Y - μ_X = 0

Alternative Hypothesis:

|μ_Y - μ_X| ≥ Δ_A

Usage

n_ttest(effect, sd, alpha, power, r = 1)

Arguments

effect	Effect Δ_A used as alternative hypothesis.
sd	Standard deviation σ of the Data on the alternative hypothesis.
alpha	Significance level α.
power	Desired Power 1-β.
r	Default = 1. Quotient of Group sizes r = n_Y / n_X.

Details

[1] M.Kieser: Fallzahlberechnung in der medizinischen Forschung [2018], 1th Edition

Value

n_ttest returns an object of type list. The resulting Sample Sizes are located in entrys named n_X, n_Y, n. The resulting power is named power_out.

Examples

n_ttest(effect = 10, sd = 20, alpha = .05, power = .90)
n_ttest(effect = 10, sd = 20, alpha = .05, power = .90, r = 2)$n
n_ttest(effect = 10, sd = 20, alpha = .05, power = .90, r = 2)$power_out

goseberg/samplesizr documentation built on May 28, 2019, 8:43 a.m.