chisq.bin.exp {RVAideMemoire}

Expected counts for comparison of response probabilities to given values

Description

Returns expected counts before comparing response probabilities (i.e. when the response variable is a binary variable) to given values by a chi-squared test. The function is in fact a wrapper to the chi-squared test for comparison of proportions to given values on a contingency table.

Usage

chisq.bin.exp(formula, data, p, graph = FALSE)

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).

p

theoretical probabilities.

graph

logical. If TRUE a mosaic plot of expected counts is drawn.

Details

The function returns how many counts can be < 5 to respect Cochran's rule (80% of counts must be >= 5).

Value

p.theo

theoretical probabilities.

mat

contingency table of expected counts.

cochran

number of counts which can be < 5.

Author(s)

Maxime HERVE <[e-mail]>

See Also

prop.test, chisq.theo.bintest, mosaicplot

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])
p.theo <- c(0.5,0.45,0.2)
chisq.bin.exp(response~fact,p=p.theo)