t_test_BFF {BFF}

t_test_BFF

Description

t_test_BFF constructs BFFs based on the t test. BFFs depend on hyperparameters r and tau^2 which determine the shape and scale of the prior distributions which define the alternative hypotheses. By setting r > 1, we use higher-order moments for replicated studies. Fractional moments are set with r > 1 and r not an integer. All results are on the log scale. Plot saved to working directory unless a full path is specified in the 'savename' variable of the function.

Usage

t_test_BFF(
  t_stat,
  n = NULL,
  df = NULL,
  one_sample = TRUE,
  n1 = NULL,
  n2 = NULL,
  savename = NULL,
  maximize = FALSE,
  r = 1,
  tau2 = NULL,
  save = TRUE,
  xlab = NULL,
  ylab = NULL,
  main = NULL
)

Arguments

t_stat

T statistic

n

sample size (if one sample test)

df

degrees of freedom

one_sample

is test one sided? Default is TRUE

n1

sample size of group one for two sample test

n2

sample size of group two for two sample test

savename

optional, filename for saving the pdf of the final plot

maximize

should the function be maximzied over all possible r values? Default is FALSE. Only set to TRUE if analyzing multiple studies

r

r value

tau2

tau2 values (can be a single entry or a vector of values)

save

should a copy of the plot be saved?

xlab

optional, x label for plot

ylab

optional, y label for plot

main

optional, main label for plot

Value

Returns Bayes factor function results

BFF	The log of the Bayes Factor Function values
effect_size	Effect sizes tested (seq(0, 1, by = 0.01))
BFF_max_RMSE	Maximum BFF value
max_RMSE	Effect size that maximizes BFF
tau2	tau^2 values tested

Examples

tBFF = t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE)
t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE, tau2 = 0.5)
t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE, tau2 = c(0.5, 0.2))
t_test_BFF(t_stat = 2.5, n1 = 50, n2 = 40, df = 88, save = FALSE, one_sample = FALSE)
t_test_BFF(t_stat = 2.5, n = 50, r = 2, df = 49, save = FALSE)
t_test_BFF(t_stat = 2.5, r = 2, n1 = 50, n2 = 30, df = 78, one_sample = FALSE, save = FALSE)
t_test_BFF(t_stat = 2.5, n = 50, r = 2.5, df = 49, save = FALSE)
t_test_BFF(t_stat=2.5, r = 2.5, n1 = 50, n2 = 30, df = 78, one_sample = FALSE, save=FALSE)
t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE, maximize = TRUE)
t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE, maximize = TRUE, tau2 = 0.5)
t_test_BFF(t_stat = 2.5, n = 50, df = 49, save = FALSE, maximize = TRUE, tau2 = c(0.5, 0.8))
tBFF$BFF_max_RMSE   # maximum BFF value
tBFF$max_RMSE       # effect size which maximizes the BFF value