[R] Checking for normality and homogeneity of variance

[Alain Zuur]

Haiyang AI wrote:
> 
> Dear all,
> 
> I'm a beginner of R and I need to carry out some three-way mixed ANOVAs.
> Following examples at http://personality-project.org/r/r.anova.html, I
> managed to get the ANOVA part, but I don't know how can I check data
> normality and homogeneity of variance in R (since they're the required
> assumptions of ANOVA analysis).
> 
> 


No..normality and homogeneity of the data it is not an assumption! It is
normality and homogeneity of the residuals!

See also:
http://www3.interscience.wiley.com/cgi-bin/fulltext/122683826/PDFSTART


Alain



-----
Dr. Alain F. Zuur
First author of:

1. Analysing Ecological Data (2007).
Zuur, AF, Ieno, EN and Smith, GM. Springer. 680 p.
URL: www.springer.com/0-387-45967-7


2. Mixed effects models and extensions in ecology with R. (2009).
Zuur, AF, Ieno, EN, Walker, N, Saveliev, AA, and Smith, GM. Springer.
http://www.springer.com/life+sci/ecology/book/978-0-387-87457-9


3. A Beginner's Guide to R (2009).
Zuur, AF, Ieno, EN, Meesters, EHWG. Springer
http://www.springer.com/statistics/computational/book/978-0-387-93836-3


Other books: http://www.highstat.com/books.htm


Statistical consultancy, courses, data analysis and software
Highland Statistics Ltd.
6 Laverock road
UK - AB41 6FN Newburgh
Tel: 0044 1358 788177
Email: highstat at highstat.com
URL: www.highstat.com
URL: www.brodgar.com


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