p.adjust {base}

R Documentation

Adjust p values for multiple comparisons

Description

Given a set of p values, returns p values adjusted using one of several methods.

Usage

p.adjust(p, method=p.adjust.methods, n=length(p))
p.adjust.methods # c("holm", "hochberg", "bonferroni","none")

Arguments

p	vector of p values
method	correction method
n	number of comparisons

Details

The adjustment methods include the Bonferroni correction in which the p values are multiplied by the number of comparisons. Two less conservative corrections by Holm, respectively Hochberg, are also included. A pass-through option "none" is also included. The set of methods are contained in the p.adjust.methods vector for the benefit of methods that need to have the method as an option and pass it on to p.adjust.

Value

A vector of corrected p values.

Note

The Hochberg method is only proved to work if the p values are independent, although simulations have indicated that it works in correlated cases as well. Hence the Holm method is the default.

References

S Paul Wright: Adjusted P-values for simultaneous inference, Biometrics 48, 1005–1013

See Also

pairwise.* functions in the ctest package, such as pairwise.t.test.

Examples

  p <- runif(50)
  p.adjust(p)

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