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Справка Scilab >> Statistics > Data with Missing Values > nand2mean


difference of the means of two independent samples

Calling Sequence




real or complex vector or matrix


real or complex vector or matrix


real scalar between 0 and 1


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 functions as the probability function depends on the sizes of sample1 and sample2 (cdfnor is chosen if the samples totalize 103 values or more, else cdft is used). 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.


sample1 = 0:10;
sample2 = [90:100 %nan];

nand2mean(sample2, sample1)
// Returns mean(sample2)-mean(sample1) = 95-5 = 90, and since there are only 22 values (NaN excluded), cdft is used to return 2.9499978.
// The %nan is ignored.


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

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Last updated:
Thu Oct 02 14:01:07 CEST 2014