### Name: fisher.test ### Title: Fisher's Exact Test for Count Data ### Aliases: fisher.test ### Keywords: htest ### ** Examples ## Agresti (1990), p. 61f, Fisher's Tea Drinker ## A British woman claimed to be able to distinguish whether milk or ## tea was added to the cup first. To test, she was given 8 cups of ## tea, in four of which milk was added first. The null hypothesis ## is that there is no association between the true order of pouring ## and the woman's guess, the alternative that there is a positive ## association (that the odds ratio is greater than 1). TeaTasting <- matrix(c(3, 1, 1, 3), nrow = 2, dimnames = list(Guess = c("Milk", "Tea"), Truth = c("Milk", "Tea"))) fisher.test(TeaTasting, alternative = "greater") ## => p=0.2429, association could not be established ## Fisher (1962, 1970), Criminal convictions of like-sex twins Convictions <- matrix(c(2, 10, 15, 3), nrow = 2, dimnames = list(c("Dizygotic", "Monozygotic"), c("Convicted", "Not convicted"))) Convictions fisher.test(Convictions, alternative = "less") fisher.test(Convictions, conf.int = FALSE) fisher.test(Convictions, conf.level = 0.95)$conf.int fisher.test(Convictions, conf.level = 0.99)$conf.int ## A r x c table Agresti (2002, p. 57) Job Satisfaction Job <- matrix(c(1,2,1,0, 3,3,6,1, 10,10,14,9, 6,7,12,11), 4, 4, dimnames = list(income=c("< 15k", "15-25k", "25-40k", "> 40k"), satisfaction=c("VeryD", "LittleD", "ModerateS", "VeryS"))) fisher.test(Job) fisher.test(Job, simulate.p.value=TRUE, B=1e5)