[R] Possible bug

[Kevin Thorpe]

Take a look at:

xtabs(~Plant+Treatment, data=CO2)

It appears to me that Plant incorporates both plant and treatment for use in a mixed model context. If you notice, Treatment is not completely ignored in the second version. The DF=11 for plant whereas in the first analysis it is 10 and there is 1 for Treatment.

I may be wrong, but that is my guess.


> On Mar 17, 2022, at 10:17 AM, konrad via R-help <r-help using r-project.org> wrote:
> 
> Dear all,
> 
> 
> I recently conducted aov calculations of datasets::CO2.
> 
> 
> When I'm using the following code: 'summary(aov(CO2$uptake~CO2$Treatment*CO2$Plant))'. Everything is fine. I get a result for Plant and Treatment.
> 
> 
> However, if using: 'summary(aov(CO2$uptake~CO2$Plant*CO2$Treatment))' 'Treatment' is ignored.
> 
> I'm using R 3.6 on Linux Mint. Any idea why this happens?
> 
> 
> Regards,
> 
> 
> Konrad
> 
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-- 
Kevin E. Thorpe
Head of Biostatistics,  Applied Health Research Centre (AHRC)
Li Ka Shing Knowledge Institute of St. Michael’s Hospital
Assistant Professor, Dalla Lana School of Public Health
University of Toronto
email: kevin.thorpe using utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016