# odds_ratios: Compute (Log) Odds Ratios In REdaS: Companion Package to the Book 'R: Einführung durch angewandte Statistik'

## Description

This function computes the (log-)odds ratio (OR) for a 2 × 2 table (`x` must be an object of class `'table'` either by using `table` or `as.table`). For a `data frame` of k variables with 2 categories each, all k · (k − 1) ∕ 2 pairwise (log-)odds-ratios are computed.

## Usage

 ```1 2 3 4 5 6 7``` ```odds_ratios(x) ## S3 method for class 'REdaS_ORs' print(x, ...) ## S3 method for class 'REdaS_ORs' summary(object, ...) ```

## Arguments

 `x` either a 2 × 2 `table` object or a data frame where each variable has two categories. `object` an object of class `'REdaS_ORs'`. `...` further arguments.

## Details

Note that tables where one or more cells are 0 are not processed and a warning is issued in such cases.

## Value

`odds_ratios()` returns a list of class `'REdaS_ORs'`:

 `call` the issued function call. `x` the original data. `tables` a list of one or more tables. `comps` a list of the compared variables' names. `ORs` a list with (log-)odds-ratios, standard errors, z- and p-values.

`print.REdaS_ORs()` invisibly returns a matrix containing all statistics shown by the `print`-method.

Marco J. Maier

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24``` ```# create a table from a 2 x 2 matrix of frequencies using as.table() tab <- as.table( matrix(c(49, 1, 5, 45), 2) ) dimnames(tab) <- list("LED on?" = c("no", "yes"), "PC running?" = c("no", "yes")) tab odds_ratios(tab) # generate a matrix with 3 variables and 100 observations # note that each variable must have exactly two categories set.seed(5) x <- data.frame("A" = as.factor(sample(1:2, 100, TRUE)), "B" = as.factor(sample(3:4, 100, TRUE)), "C" = as.factor(sample(5:6, 100, TRUE))) head(x) res <- odds_ratios(x) # print the results and save the summarized information in a matrix resmat <- print(res) resmat # the summary method gives a rather lengthy output with all tables etc. summary(res) ```

REdaS documentation built on May 2, 2019, 2:48 p.m.