Biostats Calculator

Features > Wilcoxon signed-rank test

A Wilcoxon signed-rank test is used when two measurements have been made of the same subjects, and we want to know whether there is a significant difference between these measurements on average. For example, subjects could be measured before and after a treatment, in an attempt to determine whether the treatment produces an improvement.

Unlike the paired t-test, it is non-parametric and does not require the data to be normally distributed.

After selecting Wilcoxon signed-rank from the menu, simply enter the sample values for each individual. Biostats Calculator will calculate the differences between measurements and perform a hypothesis test to determine whether there is a statistically significant difference.

Biostats Calculator reports:

• The median and range of the first and second samples
• The p value, indicating how likely it is that the observed difference would occur due to chance alone
• whether the result is significant at the 95% confidence level
• The W₊ and W_- statistics which describe the magnitude of variation between the first and second sample

Biostats Calculator can perform this test and 11 others from the convenience of your iPhone or iPod Touch. Buy it today!

Related tests

• Paired t-test - a more powerful parametric test applicable if the populations being sampled are normally distributed
• Mann-Whitney U test - for comparing independent samples of two groups