pd_to_p: Convert between Probability of Direction (pd) and p-value.

In easystats/bayestestR: Understand and Describe Bayesian Models and Posterior Distributions

Convert between Probability of Direction (pd) and p-value.

Description

Enables a conversion between Probability of Direction (pd) and p-value.

Usage

pd_to_p(pd, ...)

## S3 method for class 'numeric'
pd_to_p(pd, direction = "two-sided", verbose = TRUE, ...)

p_to_pd(p, direction = "two-sided", ...)

convert_p_to_pd(p, direction = "two-sided", ...)

convert_pd_to_p(pd, ...)

Arguments

pd	A Probability of Direction (pd) value (between 0 and 1). Can also be a data frame with a column named pd, p_direction, or PD, as returned by p_direction(). In this case, the column is converted to p-values and the new data frame is returned.
...	Arguments passed to or from other methods.
direction	What type of p-value is requested or provided. Can be "two-sided" (default, two tailed) or "one-sided" (one tailed).
verbose	Toggle off warnings.
p	A p-value.

Details

Conversion is done using the following equation (see Makowski et al., 2019):

When direction = "two-sided"

p = 2 * (1 - p_d)

When direction = "one-sided"

p = 1 - p_d

Note that this conversion is only valid when the lowest possible values of pd is 0.5 - i.e., when the posterior represents continuous parameter space (see p_direction()). If any pd < 0.5 are detected, they are converted to a p of 1, and a warning is given.

Value

A p-value or a data frame with a p-value column.

References

Makowski, D., Ben-Shachar, M. S., Chen, S. H. A., and Lüdecke, D. (2019). Indices of Effect Existence and Significance in the Bayesian Framework. Frontiers in Psychology 2019;10:2767. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.3389/fpsyg.2019.02767")}

Examples

pd_to_p(pd = 0.95)
pd_to_p(pd = 0.95, direction = "one-sided")

easystats/bayestestR documentation built on Dec. 20, 2024, 8:11 p.m.