Overview for 1-Sample Sign

Use 1-Sample Sign 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, a consultant for a large company uses a 1-sample sign test to determine whether the company's median salary differs from the industry average of $45,000. 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 sign test does not make assumptions about population symmetry.

Where to find this analysis

To perform a 1-sample sign test, choose Stat > Nonparametrics > 1-Sample Sign.

When to use an alternate analysis

If your data come from a symmetric distribution, use 1-Sample Wilcoxon.
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.