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help for ^chitest6^
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Chi-square test for univariate frequency distributions
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^chitest6^ observed [ expected ] [^if^ exp] [^in^ range]
[ ^, nfit(^#^) count^ ]
Description
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^chitest6^ works on either one or two variables.
By default the first variable is taken to be observed frequencies, which must
be zeros or positive integers. Optionally, the first variable is treated as a
variable with distinct values to be counted: the observed frequencies are then
used in a chi-square test.
The second variable, if specified, is taken to be expected frequencies under
some hypothesis, which must be positive. If the second variable is not
specified, the expected frequencies are taken to be equal, i.e. equal to
the mean of the observed frequencies.
The display includes the Pearson chi-square statistic and its P-value
for a test of the hypothesis, the likelihood-ratio chi-square statistic
and its P-value, observed frequencies, expected frequencies, classic
residuals (observed - expected), and Pearson residuals, defined as
(observed - expected) / sqrt(expected).
Any cells with expected frequencies less than 5 are flagged.
Options
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^nfit^ indicates the number of parameters that have been estimated from
the data. This number will be subtracted from (number of cells - 1)
to give the number of degrees of freedom. The default is 0.
^count^ instructs ^chitest6^ to count the single variable specified, which
is treated as a categorical variable.
Examples
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. ^chitest6 count Poisson, nfit(1)^
Saved values
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r(k) number of classes in distribution
r(df) degrees of freedom
r(chi2) Pearson chi-square
r(p) P-value of Pearson chi-square
r(chi2_lr) likelihood-ratio chi-square
r(p_lr) P-value of likelihood-ratio chi-square
r(emean) mean expected frequency
Author
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Nicholas J. Cox, University of Durham, U.K.
n.j.cox@@durham.ac.uk
Also see
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Manual: [R] tabulate
On-line: help for @tabulate@, @chitest6i@ (if installed)