| % File src/library/stats/man/mcnemar.test.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2007 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{mcnemar.test} |
| \alias{mcnemar.test} |
| \title{McNemar's Chi-squared Test for Count Data} |
| \description{ |
| Performs McNemar's chi-squared test for symmetry of rows and columns |
| in a two-dimensional contingency table. |
| } |
| \usage{ |
| mcnemar.test(x, y = NULL, correct = TRUE) |
| } |
| \arguments{ |
| \item{x}{either a two-dimensional contingency table in matrix form, |
| or a factor object.} |
| \item{y}{a factor object; ignored if \code{x} is a matrix.} |
| \item{correct}{a logical indicating whether to apply continuity |
| correction when computing the test statistic.} |
| } |
| \value{ |
| A list with class \code{"htest"} containing the following components: |
| \item{statistic}{the value of McNemar's statistic.} |
| \item{parameter}{the degrees of freedom of the approximate |
| chi-squared distribution of the test statistic.} |
| \item{p.value}{the p-value of the test.} |
| \item{method}{a character string indicating the type of test |
| performed, and whether continuity correction was used.} |
| \item{data.name}{a character string giving the name(s) of the data.} |
| } |
| \details{ |
| The null is that the probabilities of being classified into cells |
| \code{[i,j]} and \code{[j,i]} are the same. |
| |
| If \code{x} is a matrix, it is taken as a two-dimensional contingency |
| table, and hence its entries should be nonnegative integers. |
| Otherwise, both \code{x} and \code{y} must be vectors or factors of the |
| same length. Incomplete cases are removed, vectors are coerced into |
| factors, and the contingency table is computed from these. |
| |
| Continuity correction is only used in the 2-by-2 case if |
| \code{correct} is \code{TRUE}. |
| } |
| \references{ |
| Alan Agresti (1990). |
| \emph{Categorical data analysis}. |
| New York: Wiley. |
| Pages 350--354. |
| } |
| \examples{ |
| ## Agresti (1990), p. 350. |
| ## Presidential Approval Ratings. |
| ## Approval of the President's performance in office in two surveys, |
| ## one month apart, for a random sample of 1600 voting-age Americans. |
| Performance <- |
| matrix(c(794, 86, 150, 570), |
| nrow = 2, |
| dimnames = list("1st Survey" = c("Approve", "Disapprove"), |
| "2nd Survey" = c("Approve", "Disapprove"))) |
| Performance |
| mcnemar.test(Performance) |
| ## => significant change (in fact, drop) in approval ratings |
| } |
| \keyword{htest} |