nand2mean - difference of the means of two independent samples

### Calling Sequence

  `[dif]=nand2mean(sample1,sample2)`
  `[dif]=nand2mean(sample1,sample2,conf)`

### Parameters

- `sample1` real or complex vector or matrix
- `sample2` real or complex vector or matrix
- `conf` real scalar between 0 and 1

### Description

This function computes an estimate (dif(1)) for the difference of the means of two independent samples (arrays sample1 and sample2) and gives the half amplitude of the range of variability of dif with an indicated confidence level (dif(2)). The choice of the normal or t fonctions as the probability fonction depends on the sizes of sample1 and sample2. We suppose that the underlying variances of both populations are equal. NAN values are not counted.

In Labostat, NAN values stand for missing values in tables.

In absence of the confidence parameter a confidence level of 95% is assumed.

### REFERENCES

Wonacott, T.H. & Wonacott, R.J.; Introductory Statistics, 5th edition, J.Wiley & Sons, 1990.