G.bintest: G-test for binary variables

In RVAideMemoire: Testing and Plotting Procedures for Biostatistics

G-test for binary variables

Description

Performs a G-test for comparing response probabilities (i.e. when the response variable is a binary variable). The function is in fact a wrapper to the G-test for comparison of proportions on a contingency table. If the p-value of the test is significant, the function performs pairwise comparisons by using G-tests.

Usage

G.bintest(formula, data, alpha = 0.05, p.method = "fdr")

Arguments

formula	a formula of the form a ~ b, where a and b give the data values and corresponding groups, respectively. a can be a numeric vector or a factor, with only two possible values (except NA).
data	an optional data frame containing the variables in the formula formula. By default the variables are taken from environment(formula).
alpha	significance level to compute pairwise comparisons.
p.method	method for p-values correction. See help of p.adjust.

Details

If the response is a 0/1 variable, the probability of the '1' group is tested. In any other cases, the response is transformed into a factor and the probability of the second level 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 fisher.bintest in that case.

Value

method.test	a character string giving the name of the global test computed.
data.name	a character string giving the name(s) of the data.
alternative	a character string describing the alternative hypothesis.
estimate	the estimated probabilities.
null.value	the value of the difference in probabilities under the null hypothesis, always 0.
statistic	test statistics.
parameter	test degrees of freedom.
p.value	p-value of the global test.
alpha	significance level.
p.adjust.method	method for p-values correction.
p.value.multcomp	data frame of pairwise comparisons result.
method.multcomp	a character string giving the name of the test computed for pairwise comparisons.

Author(s)

Maxime HERVE <[e-mail]>

See Also

chisq.bintest, fisher.bintest

Examples

response <- c(rep(0:1,c(40,60)),rep(0:1,c(55,45)),rep(0:1,c(65,35)))
fact <- gl(3,100,labels=LETTERS[1:3])
G.bintest(response~fact)

RVAideMemoire documentation built on Nov. 6, 2023, 5:07 p.m.