WRS2 (version 0.3-1)

yuen: Robust t-tests to compare independent means.

Description

The function yuen performs Yuen's test for trimmed means, yuenbt is a bootstrap version of it. The pb2gen function performs a t-test based on various robust estimators.

Usage

yuen(formula, data, tr = 0.2)
yuenbt(formula, data, tr = 0.2, nboot = 599, side = FALSE)
pb2gen(formula, data, est = "mom", nboot = 599)

Arguments

formula

an object of class formula.

data

an optional data frame for the input data.

tr

trim level for the mean.

nboot

number of bootstrap samples.

side

if TRUE the confidence intervals are forced to be symmetric.

est

Estimate to be used for the group comparisons: either "onestep" for one-step M-estimator of location using Huber's Psi, "mom" for the modified one-step (MOM) estimator of location based on Huber's Psi, or "median", <

Value

• Returns an object of class "yuen" containing:
• test
  value of the test statistic (F-statistic)
• p.value
  p-value
• conf.int
  confidence interval
• call
  function call

Details

In order to get a p-value for yuenbt, side needs to be set to TRUE.

References

Wilcox, R. (2012). Introduction to Robust Estimation and Hypothesis Testing (3rd ed.). Elsevier.

See Also

t1way,t1waybt

Examples

## Yuen's test
yuen(Anxiety ~ Group, data = spider)

## Bootstrap version of Yuen's test (symmetric CIs)
yuenbt(Anxiety ~ Group, data = spider, side = TRUE)

## Using an M-estimator
pb2gen(Anxiety ~ Group, data = spider, est = "mom")
pb2gen(Anxiety ~ Group, data = spider, est = "mean")
pb2gen(Anxiety ~ Group, data = spider, est = "median")