Bootstrapped SMD Calculation

A function to only calculate standardized mean differences with bootstrap confidence intervals.

boot_smd_calc(
  x,
  ...,
  paired = FALSE,
  var.equal = FALSE,
  alpha = 0.05,
  bias_correction = TRUE,
  rm_correction = FALSE,
  glass = NULL,
  boot_ci = c("stud", "basic", "perc"),
  R = 1999
)

# S3 method for default
boot_smd_calc(
  x,
  y = NULL,
  paired = FALSE,
  var.equal = FALSE,
  alpha = 0.05,
  mu = 0,
  bias_correction = TRUE,
  rm_correction = FALSE,
  glass = NULL,
  boot_ci = c("stud", "basic", "perc"),
  R = 1999,
  ...
)

# S3 method for formula
boot_smd_calc(formula, data, subset, na.action, ...)

Arguments

x

a (non-empty) numeric vector of data values.

...

further arguments to be passed to or from methods.

paired

a logical indicating whether you want a paired t-test.

var.equal

a logical variable indicating whether to treat the two variances as being equal. If TRUE then the pooled variance is used to estimate the variance otherwise the Welch (or Satterthwaite) approximation to the degrees of freedom is used.

alpha

alpha level (default = 0.05)

bias_correction

Apply Hedges' correction for bias (default is TRUE).

rm_correction

Repeated measures correction to make standardized mean difference Cohen's d(rm). This only applies to repeated/paired samples. Default is FALSE.

glass

A option to calculate Glass's delta as an alternative to Cohen's d type SMD. Default is NULL to not calculate Glass's delta, "glass1" will use the first group's SD as the denominator whereas "glass2" will use the 2nd group's SD.

boot_ci

type of bootstrap confidence interval. Options include studentized (stud), empirical/basic (basic) and percentile (perc) confidence intervals.

R

number of bootstrap replicates

y

an optional (non-empty) numeric vector of data values.

mu

Null value. Deviating from zero will give the x-y-mu.

formula

a formula of the form lhs ~ rhs where lhs is a numeric variable giving the data values and rhs either 1 for a one-sample or paired test or a factor with two levels giving the corresponding groups. If lhs is of class "Pair" and rhs is 1, a paired test is done.

data

an optional matrix or data frame (or similar: see model.frame) containing the variables in the formula formula. By default the variables are taken from environment(formula).

subset

an optional vector specifying a subset of observations to be used.

na.action

a function which indicates what should happen when the data contain NAs. Defaults to getOption("na.action").

Value

A data frame containing the SMD estimates.

Details

For details on the calculations in this function see vignette("SMD_calcs").

See also

Other effect sizes: boot_ses_calc(), ses_calc(), smd_calc()

Examples

if (FALSE) {
boot_smd_calc(formula = extra ~ group,data = sleep, paired = TRUE, smd_ci = "nct")
}