https://github.com/cran/bayestestR
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Tip revision: d8462ad2168ad7ee61c0d7e679174e775f01a9be authored by Dominique Makowski on 18 January 2020, 07:10 UTC
version 0.5.0
Tip revision: d8462ad
p_significance.Rd
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/p_significance.R
\name{p_significance}
\alias{p_significance}
\alias{p_significance.numeric}
\alias{p_significance.emmGrid}
\alias{p_significance.stanreg}
\alias{p_significance.brmsfit}
\title{Practical Significance (ps)}
\usage{
p_significance(x, ...)

\method{p_significance}{numeric}(x, threshold = "default", ...)

\method{p_significance}{emmGrid}(x, threshold = "default", ...)

\method{p_significance}{stanreg}(
  x,
  threshold = "default",
  effects = c("fixed", "random", "all"),
  parameters = NULL,
  verbose = TRUE,
  ...
)

\method{p_significance}{brmsfit}(
  x,
  threshold = "default",
  effects = c("fixed", "random", "all"),
  component = c("conditional", "zi", "zero_inflated", "all"),
  parameters = NULL,
  verbose = TRUE,
  ...
)
}
\arguments{
\item{x}{Vector representing a posterior distribution. Can also be a \code{stanreg} or \code{brmsfit} model.}

\item{...}{Currently not used.}

\item{threshold}{The threshold value that separates significant from negligible effect. If \code{"default"}, the range is set to \code{0.1} if input is a vector, and based on \code{\link[=rope_range]{rope_range()}} if a Bayesian model is provided.}

\item{effects}{Should results for fixed effects, random effects or both be returned?
Only applies to mixed models. May be abbreviated.}

\item{parameters}{Regular expression pattern that describes the parameters that
should be returned. Meta-parameters (like \code{lp__} or \code{prior_}) are
filtered by default, so only parameters that typically appear in the
\code{summary()} are returned. Use \code{parameters} to select specific parameters
for the output.}

\item{verbose}{Toggle off warnings.}

\item{component}{Should results for all parameters, parameters for the conditional model
or the zero-inflated part of the model be returned? May be abbreviated. Only
applies to \pkg{brms}-models.}
}
\value{
Values between 0 and 1 corresponding to the probability of practical significance (ps).
}
\description{
Compute the probability of \strong{Practical Significance} (\strong{\emph{ps}}), which can be conceptualized as a unidirectional equivalence test. It returns the probability that effect is above a given threshold corresponding to a negligible effect in the median's direction. Mathematically, it is defined as the proportion of the posterior distribution of the median sign above the threshold.
}
\details{
\code{p_significance()} returns the proportion of a probability
  distribution (\code{x}) that is outside a certain range (the negligible
  effect, or ROPE, see argument \code{threshold}). If there are values of the
  distribution both below and above the ROPE, \code{p_significance()} returns
  the higher probability of a value being outside the ROPE. Typically, this
  value should be larger than 0.5 to indicate practical significance. However,
  if the range of the negligible effect is rather large compared to the
  range of the probability distribution \code{x}, \code{p_significance()}
  will be less than 0.5, which indicates no clear practical significance.
}
\examples{
library(bayestestR)

# Simulate a posterior distribution of mean 1 and SD 1
# ----------------------------------------------------
posterior <- rnorm(1000, mean = 1, sd = 1)
p_significance(posterior)

# Simulate a dataframe of posterior distributions
# -----------------------------------------------
df <- data.frame(replicate(4, rnorm(100)))
p_significance(df)

# rstanarm models
# -----------------------------------------------
library(rstanarm)
model <- rstanarm::stan_glm(mpg ~ wt + cyl,
  data = mtcars,
  chains = 2, refresh = 0
)
p_significance(model)
}
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