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.
Usage
wilcoxon(
var1,
var2 = NULL,
alternative = "two.sided",
null.hypoth = 0,
paired = FALSE,
exact = FALSE,
correct = FALSE,
conf.int = FALSE,
conf.level = 0.95
)Arguments
- var1
numeric vector of data values. Non-finite (missing or infinite) values will be omitted.
- var2
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".- null.hypoth
the value of the null hypothesis.
- paired
logical indicating whether the data are paired or not. Default is
FALSE. IfTRUE, 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
- conf.level
confidence level for the interval. Defaults to 0.95.
Value
A list of 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
null.hypoth.- 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.
Details
In the one-sample case, the returned confidence interval (when conf.int = TRUE)
is a confidence interval for the pseudo-median of the underlying distribution. In the two-sample
case, the function returns a confidence interval for the median of the difference between samples from
the two distributions. See wilcox.test for more information.
Examples
#- 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)
#>
#> 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
#>
#> unadjusted variance 204.75
#> adjustment for ties 0.00
#> adjustment for zeroes 0.00
#> adjusted variance 204.75
#> H0 Ha
#> Hypothesized Median 0 two.sided
#> Test Statistic p-value
#> Z 1.7821 0.074735
#- Perform the test -#
wilcoxon(cf, healthy, conf.int=TRUE)
#>
#> Wilcoxon rank sum test
#> obs rank sum expected
#> cf 13 194 175.5
#> healthy 13 157 175.5
#> combined 26 351 351.0
#>
#> unadjusted variance 380.25
#> adjustment for ties 0.00
#> adjusted variance 380.25
#> H0 Ha
#> Hypothesized Median 0 two.sided
#> Test Statistic p-value CI Point Estimate
#> Z 0.94872 0.34276 [-172, 340] 62