Epi (version 2.7)

twoby2: Analysis of a two by two table

Description

Computes the usual measures of association in a 2 by 2 table with confidence intervals. Also produces asymtotic and exact tests. Assumes that comparison of probability of the first column level between levels of the row variable is of interest. Output requires that the input matrix has meaningful row and column labels.

Usage

twoby2(exposure, outcome, alpha = 0.05, print = TRUE, dec = 4, conf.level = 1-alpha, F.lim = 10000)

Arguments

exposure

If a table the analysis is based on the first two rows and first two columns of this. If a variable, this variable is tabulated against

outcome

as the second variable

alpha

Significance level

print

Should the results be printed?

dec

Number of decimals in the printout.

conf.level

1-alpha

F.lim

If the table total exceeds F.lim, Fisher's exact test is not computed

Value

Examples

Treat <- sample(c("A","B"), 50, rep=TRUE )
Resp <- c("Yes","No")[1+rbinom(50,1,0.3+0.2*(Treat=="A"))]
twoby2( Treat, Resp )                 
twoby2( table( Treat, Resp )[,2:1] ) # Comparison the other way round