[R] two questions

[David Winsemius]

The usual least-squares methods are fairly robust to departures from  
normality. Furthermore, it is the residuals that are assumed to be  
normally distributed (not the marginal distributions that you are  
probably looking at) , so it does not sound as though you have yet  
examined the data properly. Tell us what the descriptive stats (say  
the means, variance, 10th and 90th percentiles) are on the residuals  
within cells cross-classified by the gender and city-of-birth  
variables (say the means, variance, 10th and 90th percentiles).

On Sep 6, 2010, at 4:34 PM, Iasonas Lamprianou wrote:

>
> Dear friends, two questions
>
> (1) does anyone know if there are any non-parametric equivalents of  
> the two-way ANOVA in R? I have an ordinal non-normally distributed  
> dependent variable and two factors (gender and city of birth).  
> Normally, one would try a two-way anova, but if R has any non- 
> parametric equivalents, that might be great.

There is an entire task view page on robust methods if you decide to  
press on with this quest.

> (2) Also, if the interaction of gender and city of birth is  
> statistically significant, which post-hoc tests should I run?

How many cities are we talking about?

> Thanks
>
> Jason
>
>
> Dr. Iasonas Lamprianou

--

David Winsemius, MD
West Hartford, CT