pd_to_p {bayestestR}

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, 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, direction = "two-sided", verbose = TRUE, ...)

Arguments

pd

A Probability of Direction (pd) value (between 0 and 1).

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.

...

Arguments passed to or from other methods.

p

A p-value.

Details

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

When direction = "two-sided" -

p = 2 \times (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.

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. doi:10.3389/fpsyg.2019.02767

Examples

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