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binom.test {ctest}R Documentation

Exact Binomial Test

Description

Performs an exact test of the null that the probability of success in a Bernoulli experiment of length n is p, based on the number x of successes observed.

Usage

binom.test(x, n, p = 0.5, alternative = c("two.sided", "less", "greater"),
           conf.level = 0.95)

Arguments

x

number of successes.

n

number of trials.

p

probability of success.

alternative

indicates the alternative hypothesis and must be one of "two.sided", "greater" or "less". You can specify just the initial letter.

conf.level

confidence level for the returned confidence interval.

Value

A list with class "htest" containing the following components:

statistic

the number of successes, x.

parameter

the number of trials, n.

p.value

the p-value of the test.

conf.int

a confidence interval for the probability of success.

estimate

the estimated probability of success, x / n.

null.value

the probability of success under the null, p.

alternative

a character string describing the alternative hypothesis.

method

the string "Exact binomial test".

data.name

a character string giving the names of the data.

References

Conover, W. J. (1971), Practical nonparametric statistics. New York: John Wiley & Sons. Pages 97–104.

Myles Hollander & Douglas A. Wolfe (1973), Nonparametric statistical inference. New York: John Wiley & Sons. Pages 15–22.

See Also

prop.test for a general (approximate) test for equal or given proportions.

Examples

## Conover (1971), p. 97f.
## Under (the assumption of) simple Mendelian inheritance, a cross
##  between plants of two particular genotypes produces progeny 1/4 of
##  which are ``dwarf'' and 3/4 of which are ``giant'', respectively.
##  In an experiment to determine if this assumption is reasonable, a
##  cross results in progeny having 243 dwarf and 682 giant plants.
##  If ``giant'' is taken as success, the null hypothesis is that p =
##  3/4 and the alternative that p != 3/4.
binom.test(682, 682 + 243, p = 3/4)
## => Data are in agreement with the null hypothesis.