pwr.t.test.contour: Plot a Power Contour for a t-test comparison

In mathesong/pwrcontour: Power Contours And Tables For Different Hypothetical Effect Sizes

Description

Plot a contour of sample size, effect size and power for t-test comparisons in the style of Richard Morey's jpower JAMOVI module.

Usage

pwr.t.test.contour(
  nmin,
  nmax,
  esmin,
  esmax,
  sig.level = 0.05,
  type = c("two.sample", "one.sample", "paired"),
  alternative = c("two.sided", "less", "greater"),
  pwrbands = c(0.5, 0.8, 0.95),
  d_unitconversion = 1,
  d_units = "Cohen's d",
  alpha = 0.6
)

Arguments

nmin	Minimum sample size for the plot.
nmax	Maximum sample size for the plot.
esmin	Minimum effect size for the plot. Defaults to Cohen's d, but can be percentages or units of measurement if desired using the d_unitconversion parameter.
esmax	Maximum effect size for the plot. Defaults to Cohen's d, but can be percentages or units of measurement if desired using the d_unitconversion parameter.
sig.level	Significance level, or alpha. Defaults to 0.05.
type	The t-test type. The default is "two.sample", but other options are "paired" or "one.sample".
alternative	The alternative hypothesis. The default is "two.sided", but other options are "less" or "greater".
pwrbands	Additional black power bands to display on the figure to emphasise certain power levels. Defaults to c(0.5, 0.8, 0.95).
d_unitconversion	Unit conversion of Cohen's d. If specified as 5, for example, 5 units of change in the units of the figure are considered equivalent to Cohen's d = 1. This conversion should be calculated in advance. Defaults to 1 for Cohen's d.
d_units	The units of the difference. Defaults to "Cohen's d".
alpha	The transparency of the contours, in order to show grid lines below.

Value

A ggplot2 object.

Author(s)

Granville J Matheson, [e-mail]

Examples

# A straightforward example
pwr.t.test.contour(3, 100, 0.1, 1, sig.level=0.05)

# Custom units
pwr.t.test.contour(3, 100, 0.5, 5, sig.level=0.05,
                   d_unitconversion=5, d_units="mmHg")

# Adding things
pwr.t.test.contour(3, 100, 0.5, 5, sig.level=0.05,
                   d_unitconversion=5, d_units="mmHg") +
                   ggplot2::annotate("text", x=25, y=2,
                   label="We don't want to be here")

mathesong/pwrcontour documentation built on Jan. 1, 2021, 9:19 a.m.