z_score: The z-score statistic for frequency counts (corpora)

Description Usage Arguments Details Value Author(s) See Also

Description

This function computes a z-score statistic for frequency counts, based on a normal approximation to the correct binomial distribution under the random sampling model.

Usage

1
z.score(k, n, p = 0.5, correct = TRUE)

Arguments

k

frequency of a type in the corpus (or an integer vector of frequencies)

n

number of tokens in the corpus, i.e. sample size (or an integer vector specifying the sizes of different samples)

p

null hypothesis, giving the assumed proportion of this type in the population (or a vector of proportions for different types and/or different populations)

correct

if TRUE, apply Yates' continuity correction (default)

Details

The z statistic is given by

z := (k - np) / sqrt(n p (1-p))

When Yates' continuity correction is enabled, the absolute value of the numerator d := k - np is reduced by 1/2, but clamped to a non-negative value.

Value

The z-score corresponding to the specified data (or a vector of z-scores).

Author(s)

Stefan Evert

See Also

z.score.pval


corpora documentation built on May 2, 2019, 4:56 p.m.

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