AB_t2n_prop {pwrAB}

Two-Sample t-Test Power Analysis for Proportions

Description

AB_t2n_prop performs the power analysis for AB testing, and when dependent variables are proportions (between 0 and 1). It uses the Welch's t-test, which allows for the standard deviation to vary across groups.

Usage

AB_t2n_prop(prop_A = NULL, prop_B = NULL, N = NULL, percent_B = NULL,
  sig_level = NULL, power = NULL, alternative = c("two_sided", "less",
  "greater"), max_sample = 1e+07)

Arguments

prop_A

Proportion of successes in group A (between 0 and 1)

prop_B

Proportion of successes in group B (between 0 and 1)

N

Total number of observations (sum of observations for groups A and B)

percent_B

Percentage of total observations allocated to group B (between 0 and 1 - e.g. input .5 for 50%)

sig_level

Significance level (Type I error probability)

power

Power of test (1 minus Type II error probability)

alternative

Character string specifying the alternative hypothesis, must be one of "two_sided" (default), "greater" or "less"

max_sample

Maximum sample size that is searched for

Details

Exactly one of the parameters 'prop_A', 'prop_B', 'N', 'percent_B', 'sig_level', and 'power' must be passed as NULL, and the omitted parameter is determined from the others. The standard deviations for each group are calculated using the formula sqrt(prop * (1 - prop)). When 'percent_B' is the parameter omitted, two solutions may exist, in which case the smaller value will be returned. For two_sided tests, when 'prop_A' or 'prop_B' is omitted, two solutions may exist, in which case both will be reported

Value

Object of class "power.htest", a list of the arguments (including the computed one).

Examples

# Search for power given other parameters
AB_t2n_prop(prop_A = .2, prop_B = .25,
           N = 3000, percent_B = .3,
           sig_level = .05, alternative = 'two_sided')

# Search for proportion in group B required to satisfy other parameters
AB_t2n_prop(prop_A = .2, N = 3000, percent_B = .3,
power = .8, sig_level = .05,
alternative = 'two_sided')