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scipy tutorial - Baustatik-Info-Server

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References<br />

[R34]<br />

kruskal(*args)<br />

Compute the Kruskal-Wallis H-test for independent samples<br />

SciPy Reference Guide, Release 0.8.dev<br />

The Kruskal-Wallis H-test tests the null hypothesis that the population median of all of the groups are equal.<br />

It is a non-parametric version of ANOVA. The test works on 2 or more independent samples, which may have<br />

different sizes. Note that rejecting the null hypothesis does not indicate which of the groups differs. Post-hoc<br />

comparisons between groups are required to determine which groups are different.<br />

Notes<br />

Parameters<br />

sample1, sample2, ... : array_like<br />

Two or more arrays with the sample measurements can be given as arguments.<br />

Returns<br />

H-statistic : float<br />

The Kruskal-Wallis H statistic, corrected for ties<br />

p-value : float<br />

The p-value for the test using the assumption that H has a chi square distribution<br />

Due to the assumption that H has a chi square distribution, the number of samples in each group must not be too<br />

small. A typical rule is that each sample must have at least 5 measurements.<br />

References<br />

[R22]<br />

friedmanchisquare(*args)<br />

Computes the Friedman test for repeated measurements<br />

The Friedman test tests the null hypothesis that repeated measurements of the same individuals have the same<br />

distribution. It is often used to test for consistency among measurements obtained in different ways. For example,<br />

if two measurement techniques are used on the same set of individuals, the Friedman test can be used to<br />

determine if the two measurement techniques are consistent.<br />

Notes<br />

Parameters<br />

measurements1, measurements2, measurements3... : array_like<br />

Arrays of measurements. All of the arrays must have the same number of elements.<br />

At least 3 sets of measurements must be given.<br />

Returns<br />

friedman chi-square statistic : float<br />

the test statistic, correcting for ties<br />

p-value : float<br />

the associated p-value assuming that the test statistic has a chi squared distribution<br />

Due to the assumption that the test statistic has a chi squared distribution, the p-vale is only reliable for n > 10<br />

and more than 6 repeated measurements.<br />

3.18. Statistical functions (<strong>scipy</strong>.stats) 663

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