# Compute sample size for two sample Wilcoxon (Mann-Whitney) test

### Description

Compute sample size to test the hypothesis that two samples come from
the same population against that *Y*'s tend to be larger than *X*'s.

### Usage

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### Arguments

`a` |
Significance level of test. |

`b` |
Desired power of test. |

`c` |
Proportion of observations in group 1: |

`pxy` |
A value for the probability |

`two.sided` |
If |

### Details

Given two independent samples *X_1, ..., X_m* and *Y_1, ..., Y_n*,
we want to test the hypothesis that the two samples come from the same population against that
*Y*'s tend to be larger than *X*'s.

### Value

`m` |
Sample size of the first group. |

`n` |
Sample size of the second group. |

### Author(s)

Kaspar Rufibach

kaspar.rufibach@gmail.com

### References

Nother, G.E. (1987).
Sample Size Determination for Some Common Nonparametric Tests
*JASA*, **82**, 644–647.

### Examples

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