# wilcoxon: Wilcoxon Signed Rank and Mann-Whitney-Wilcoxon Rank Sum Test In uwIntroStats: Descriptive Statistics, Inference, Regression, and Plotting in an Introductory Statistics Course

## Description

Performs Wilcoxon signed rank test or Mann-Whitney-Wilcoxon rank sum test depending on data and logicals entered. Relies heavily on the function `wilcox.test`. Adds formatting and variances, and prints the z-score and p-value in addition to the test statistic and p-value.

## Usage

 ```1 2 3``` ```## S3 method for class 'wilcoxon' wilcoxon(y, x=NULL, alternative="two.sided", mu=0, paired=FALSE, exact=NULL, correct=FALSE, conf.int=FALSE, conf.level=0.95) ```

## Arguments

 `y` numeric vector of data values. Non-finite (missing or infinite) values will be omitted. `x` optional numeric vector of data values. Non-finite (missing or infinite) values will be omitted. `alternative` specifies the alternative hypothesis for the test; acceptable values are `"two.sided"`, `"greater"`, or `"less"`. `mu` the value of the null hypothesis. `paired` logical indicating whether the data are paired or not. Default is `FALSE`. If `TRUE`, data must be the same length. `exact` logical value indicating whether or not an exact test should be computed. `correct` logical indicating whether or not a continuity correction should be used and displayed. `conf.int` logical indicating whether or not to calculate and display a 'confidence interval' (performs a semi-parametric test on medians, and is non-robust) and point estimate. `conf.level` confidence level for the interval. `...` only used in the generic S3 class.

See above.

## Value

A list with class `"wilcoxon"` is returned. The print method lays out the information in an easy to read format.

 `statistic` the value of the test statistic with a name describing it. `parameter` the parameter(s) for the exact distribution of the test statistic. `p.value` the p-value for the test (calculated for the test statistic). `null.value` the parameter `mu`. `alternative` character string describing the alternative hypothesis. `method` the type of test applied. `data.name` a character string giving the names of the data. `conf.int` a confidence interval for the location parameter (only present if the argument `conf.int=TRUE`). `estimate` an estimate of the location parameter (only present if the argument `conf.int=TRUE`). `table` a formatted table of rank sum and number of observation values, for printing. `vars` a formatted table of variances, for printing. `hyps` a formatted table of the hypotheses, for printing. `inf` a formatted table of inference values, for printing.

## Author(s)

Scott S. Emerson, M.D., Ph.D., Andrew J. Spieker, Brian D. Williamson

`wilcox.test`

## Examples

 ```1 2 3 4 5 6 7 8 9``` ```#- Create the data -# cf <- c(1153, 1132, 1165, 1460, 1162, 1493, 1358, 1453, 1185, 1824, 1793, 1930, 2075) healthy <- c(996, 1080, 1182, 1452, 1634, 1619, 1140, 1123, 1113, 1463, 1632, 1614, 1836) #- Perform the test -# wilcoxon(cf, healthy, paired=TRUE) #- Perform the test -# wilcoxon(cf, healthy, conf.int=TRUE) ```

### Example output

```Attaching package: 'uwIntroStats'

The following object is masked from 'package:base':

tabulate

Wilcoxon signed rank test
obs sum ranks expected
positive  10        71     45.5
negative   3        20     45.5
zero       0         0      0.0
all       13        91     91.0

H0 Ha
Hypothesized Median 0  two.sided
Test Statistic p-value
V 71             0.080322
Z 1.7821         0.037368

Wilcoxon rank sum test
obs rank sum expected
Y         13      157    175.5
X         13      194    175.5
combined  26      351    351.0