RVAideMemoire (version 0.9-45-2)

G.test: G-test

Description

Perfoms a G-test on a contingency table or a vector of counts.

Usage

G.test(x, p = rep(1/length(x), length(x)))

Arguments

x

a numeric vector or matrix (see Details).

p

theoretical proportions (optional).

Value

• method
  name of the test.
• statistic
  test statistics.
• parameter
  test degrees of freedom.
• p.value
  p-value.
• data.name
  a character string giving the name(s) of the data.
• observed
  the observed counts.
• expected
  the expected counts under the null hypothesis.

Details

If x is matrix, it must be constructed like this: - 2 columns giving number of successes (left) and fails (right) - 1 row per population. The function works as chisq.test : - if x is a vector and theoretical proportions are not given, equality of counts is tested - if x is a vector and theoretical proportions are given, equality of counts to theoretical counts (given by theoretical proportions) is tested - if x is a matrix with two coloums, equality of proportion of successes between populations is tested. - if x is a matrix with more than two coloums, independence of rows and columns is tested. Since a G-test is an approximate test, an exact test is preferable when the number of individuals is small (200 is a reasonable minimum). See multinomial.test in that case with a vector, fisher.test with a matrix.

See Also

chisq.test, multinomial.test, fisher.test G.multcomp, G.theo.multcomp, pairwise.G.test

Examples

counts <- c(49,30,63,59)
G.test(counts)