odds.ratio: Odds Ratio for 2X2 Contingency Tables

In abd: The Analysis of Biological Data

Description

This function calculates the odds ratio for a 2 X 2 contingency table and a confidence interval (default conf.level is 95 percent) for the estimated odds ratio. x should be a matrix or data.frame. "Successes" should be located in column 1 of x, and the treatment of interest should be located in row 2. The odds ratio is calculated as (Odds row 2) / (Odds row 1). The confidence interval is calculated from the log(OR) and backtransformed.

Usage

odds.ratio(x, conf.level = 0.95)

Arguments

x	a 2 X 2 matrix or data.frame of counts
conf.level	the confidence interval level

Value

p1, p2	Proportions for rows 1 and 2
o1, o2	Odds for rows 1 and 2
OR	Odds ratio
lower	the lower bound of the confidence interval
upper	the upper bound of the confidence interval
conf.level	the confidence interval level

Author(s)

Kevin Middleton ([e-mail])

See Also

chisq.test, Aspirin

Examples

M1 <- matrix(c(14, 38, 51, 11), nrow = 2)
M1
odds.ratio(M1)

M2 <- matrix(c(18515, 18496, 1427, 1438), nrow = 2)
rownames(M2) <- c("Placebo", "Aspirin")
colnames(M2) <- c("No", "Yes")
M2
odds.ratio(M2)

abd documentation built on May 2, 2019, 4:46 p.m.