[ Collection: Introduction to R ]
Assuming that you have a contingency table that is stored in a variable called mytable
, you calculate a chi-square test using the chisq.test
command as follows:
chisq.test(mytable, correct = FALSE)
The option correct = FALSE
ensures that the standard chi-square test is calculated, i.e., that no corrections are applied. If more than a quarter of the cells in your table have an expected value smaller than 5, you should use Yates' continuity correction; you can do this by not adding the correct
option at all (i.e., R applies the correction by default), or by using the option correct = TRUE
.
By default, R does not show the expected frequencies or the residuals, but they are created as internal variables by the chi.square()
function internally, and you can force R to output them by attaching the name of the internal variable to the function, separated by a $
sign:
To show the expected frequencies, attach the option expected to the end of the command, separated by a $ sign:
chisq.test(mytable, correct = FALSE)$expected
or
chisq.test(mytable, correct = FALSE)$residuals