Wilcoxon Rank Sum Test

Non-parameter Statistic #Statistics Deal with problem with the following characteristics:

1. The problem objective is to compare two populations
2. The data are either ordinal or interval where the normality requirement necessary to perform the equal-variances t-test of ${\mu }_1-{\mu }_2$ is satisfied
3. The samples are independent.

The Hypothesis

$H_0$: The 2 population locations are the same.

$H_1$: The location of population 1 is to the left of the location of population 2

Test statistic:

排序方式：全部排序！

Example:

From small to big