chisq.test(x, y = NULL, correct = TRUE, p = rep(1/length(x), length(x)))
x
| a vector or matrix. |
y
|
a vector; ignored if x is a matrix.
|
correct
| a logical indicating whether to apply continuity correction when computing the test statistic. |
chisq.test
performs chi-square tests on contingency tables.
If x
is a matrix with one row or column, or if x
is a
vector and y
is not given, x
is treated as a
one-dimensional contingency table. In this case, the hypothesis
tested is whether the population probabilities equal those in
p
, or are all equal if p
is not given.
If x
is a matrix with at least two rows and columns, it is
taken as a two-dimensional contingency table, and hence its entries
should be nonnegative integers. Otherwise, x
and y
must
be vectors or factors of the same length; incomplete cases are
removed, the objects are coerced into factor objects, and the
contingency table is computed from these. Then, Pearson's chi-square
test of the null that the joint distribution of the cell counts in a
2-dimensional contigency table is the product of the row and column
marginals is performed. Continuity correction is only used in the
2-by-2 case if correct
is TRUE
.
"htest"
containing the following components:
statistic
| the value the chi-square test statistic. |
parameter
| the degrees of freedom of the approximate chi-square distribution of the test statistic. |
p.value
| the p-value for the test. |
method
| a character string indicating the type of test performed, and whether continuity correction was used. |
data.name
| a character string giving the name(s) of the data. |
observed
| the observed counts. |
expected
| the expected counts under the null hypothesis. |
data(insects) # Not really a good example chisq.test(insects$count > 7, insects$spray) # Prints test summary chisq.test(insects$count > 7, insects$spray)$obs # Counts observed chisq.test(insects$count > 7, insects$spray)$obs # Counts expected under the null