[R] multilevel analysis

[Daniel Nordlund]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of srecko joksimovic
> Sent: Monday, September 30, 2013 3:22 PM
> To: David Winsemius
> Cc: R help
> Subject: Re: [R] multilevel analysis
> 
> I thought so, but then I found this:
> "Normality
> 
> The assumption of normality states that the error terms at every level of
> the model are normally distributed"
> 
> maybe I misinterpreted something.
> 

Yes, error terms (i.e. residuals), not your raw data, should be normally distributed if you are going to conduct significance tests that rely on the assumption of normality.  But as David said, the assumption of normality (in any form) is not necessary for estimating linear models.

Dan


> 
> On Mon, Sep 30, 2013 at 3:06 PM, David Winsemius
> <dwinsemius at comcast.net>wrote:
> 
> >
> > On Sep 30, 2013, at 2:50 PM, srecko joksimovic wrote:
> >
> > > I have an example of multilevel analysis with 3 levels, but data are
> > > non-normally distributed. In case of normal distribution, I would
> perform
> > > multilevel linear analysis using lme function, but what should I do in
> > case
> > > of non-normal distribution?
> > >
> >
> > But normal distribution is not a requirement for linear models. Please
> > review your theory.
> >
> > > thanks,
> > > Srecko
> > >
> > >       [[alternative HTML version deleted]]
> > >
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> >
> > David Winsemius
> > Alameda, CA, USA
> >
> >
>

Daniel Nordlund
Bothell, WA USA