Overview for 1-Sample Wilcoxon

Use 1-Sample Wilcoxon to estimate the population median and to compare it to a target value or a reference value. Using this analysis, you can do the following:
  • Determine whether the population median differs from the hypothesized median that you specify.
  • Calculate a range of values that is likely to include the population median.

For example, an analyst uses a 1-sample Wilcoxon test to determine whether the median time for a newly developed drug to relieve symptoms is 12 minutes. If the median differs from the target, the analyst uses the confidence interval to determine how large the difference is likely to be and whether that difference has practical significance.

The 1-sample Wilcoxon test assumes the data come from a symmetric distribution, such as the uniform or Cauchy distributions.

Where to find this analysis

To perform a 1-sample Wilcoxon analysis, choose Stat > Nonparametrics > 1-Sample Wilcoxon.

When to use an alternate analysis

  • If your data do not come from a symmetric distribution, use 1-Sample Sign.

  • If you have more than 20 observations, or if your data aren't severely skewed, use 1-Sample t because the test has more power.