Chi-square test for univariate frequency distributions ------------------------------------------------------
^chitest6^ observed [ expected ] [^if^ exp] [^in^ range] [ ^, nfit(^#^) count^ ]
Description -----------
^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 -------
^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 --------
. ^chitest6 count Poisson, nfit(1)^
Saved values ------------
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 ------
Nicholas J. Cox, University of Durham, U.K. n.j.cox@@durham.ac.uk
Also see --------
Manual: [R] tabulate On-line: help for @tabulate@, @chitest6i@ (if installed)