tidyBF (version 0.4.0)

bf_ttest: Bayes Factor for t-test

Description

Bayes Factor for t-test

Usage

bf_ttest(
  data,
  x,
  y = NULL,
  subject.id = NULL,
  paired = FALSE,
  test.value = 0,
  bf.prior = 0.707,
  ...
)

Arguments

data

A dataframe (or a tibble) from which variables specified are to be taken. A matrix or tables will not be accepted.

x

Either the grouping variable from the dataframe data if it's a two-sample t-test or a numeric variable if it's a one-sample t-test.

y

The column in data containing the response (outcome) variable to be plotted on the y-axis. Can be entered either as a character string (e.g., "y") or as a bare expression (e.g, y).

subject.id

In case of repeated measures design (paired = TRUE, i.e.), this argument specifies the subject or repeated measures id. Note that if this argument is NULL (which is the default), the function assumes that the data has already been sorted by such an id by the user and creates an internal identifier. So if your data is not sorted and you leave this argument unspecified, the results can be inaccurate.

paired

Decides whether the design is repeated measures or not (Default: FALSE).

test.value

A number specifying the value of the null hypothesis (Default: 0).

bf.prior

A number between 0.5 and 2 (default 0.707), the prior width to use in calculating Bayes factors.

...

Arguments passed on to bf_extractor

conf.level

Confidence/Credible Interval (CI) level. Default to 0.95 (95%).

centrality

The point-estimates (centrality indices) to compute. Character (vector) or list with one or more of these options: "median", "mean", "MAP" or "all".

conf.method

The type of index used for Credible Interval. Can be "hdi" (default, see bayestestR::hdi()), "eti" (see bayestestR::eti()) or "si" (see bayestestR::si()).

k

Number of digits after decimal point (should be an integer) (Default: k = 2L).

top.text

Text to display as top.text (will be displayed on top of the Bayes Factor top.text/message).

output

If "expression", will return expression with statistical details, while "dataframe" will return a dataframe containing the results.

Details

If y is NULL, a one-sample t-test will be carried out, otherwise a two-sample t-test will be carried out.

See Also

bf_contingency_tab, bf_corr_test, bf_oneway_anova

Examples

# NOT RUN {
# ------------------- two-samples tests -----------------------------------

# for reproducibility
set.seed(123)
library(tidyBF)

# to get dataframe (between-subjects)
bf_ttest(
  data = mtcars,
  x = am,
  y = wt,
  paired = FALSE,
  bf.prior = 0.880,
  output = "dataframe"
)

# to get expression (within-subjects)
bf_ttest(
  data = dplyr::filter(bugs_long, condition %in% c("LDLF", "LDHF")),
  x = condition,
  y = desire,
  subject.id = subject,
  paired = TRUE,
  bf.prior = 0.880,
  output = "dataframe"
)

# ------------------- one-samples test -----------------------------------

# to get expression
bf_ttest(
  data = iris,
  x = Sepal.Length,
  test.value = 5.85,
  output = "expression"
)
# }