Cuzick's test for trend

Perform the Cuzick's test on trend.
This function provides a Wilcoxon-type test for trend across a group of three or more independent random samples. Assumptions:
Data must be at least ordinal

Groups must be selected in a meaningful order i.e. ordered If you do not choose to enter your own group scores then scores are allocated uniformly (1 ... n) in order of selection of the n groups. The null hypothesis of no trend across the groups T will have mean E(T), variance var(T) and the null hypothesis is tested using the normalised test statistic z. A logistic distribution is assumed for errors. Please note that this test is more powerful than the application of the Wilcoxon rank-sum / Mann-Whitney test between more than two groups of data. Cuzick J. A Wilcoxon-Type Test for Trend. Statistics in Medicine 1985;4:87-89.

Created by Giuseppe Cardillo
giuseppe.cardillo-edta@poste.it

To cite this file, this would be an appropriate format: Cardillo G. (2008) Cuzick's test: A Wilcoxon-Type Test for Trend http://www.mathworks.com/matlabcentral/fileexchange/22059