Hi, I am Biologist preparing a class on experiments in ecology including
a short and simple text about how to use and to choose the most commom
statistical tests (chi-square, t tests, ANOVA, correlation and regression).
I am planning to include the idea that testing the assumptions for
parametric tests (normality and homocedasticity) is very important
to decide between a parametric (e.g., ANOVA) or the non parametric
test (e. g. Kruskal-Wallis). I am using the Shapiro-Wilk and the Levene
test for the assumption testing but..........
While consulting people from depts of statistics about this, a few of them
were arguing that these assumption testing are just a "legend" and that
there is no problem in not respecting them !
It seems to me that normal distribution is not very important for some tests
like t tests and ANOVA but........ anyway.........
What is correct ??? What I will teach to my students ???
To test or not to test the assumptions of parametric tests: thats the
question.....
Thanks for any help !!!!
Voltolini
_____________________________________________________
Prof. J. C. Voltolini
Grupo de Estudos em Ecologia de Mamiferos - ECOMAM
Universidade de Taubate - Depto. Biologia
Praca Marcellino Monteiro 63, Bom Conselho,
Taubate, SP - BRASIL. 12030-010
TEL: 0XX12-2254165 (lab.), 2254277 (depto.)
FAX: 0XX12-2322947
E-Mail: [EMAIL PROTECTED]
____________________________________________________
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