# Signed rank sum test (one sample)

## Description

The Signed rank sum test is a test for symmetry about a test value. This test is the non-parametric alternative for the One sample t-test. It can be used when the observations are not Normally distributed.

## Required input

- Select the variable of interest.
- Optionally select a filter to include a subset of cases.
- Test value: the value you want to compare the sample data with.

## Results

The Signed rank sum test ranks the absolute values of the differences between the sample data and the test value, and calculates a statistic on the number of negative and positive differences. If the resulting P-value is small (P<0.05), then the sample data are not symmetrical about the test value and therefore a statistically significant difference can be accepted between the sample median and the test value.

## Literature

- Altman DG (1991) Practical statistics for medical research. London: Chapman and Hall.

## See also

- Mann-Whitney test (independent samples)
- Wilcoxon test (paired samples)
- More help on variables
- More help on filters