[R-sig-ME] mixed model for nested factor?
thierry.onkelinx at inbo.be
Mon May 8 20:35:29 CEST 2017
IMHO you want to detect a potential effect of warming. The amount of
warming seems to be less relevant. Therefore I'd recode temperature into a
factor with two levels: warming = yes and warming = no.
Then add the interaction between warming and season to the model. That will
take care of the difference in warming between spring and fall.
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to say
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey
2017-05-08 16:13 GMT+02:00 Jinsong Zhao <jszhao op yeah.net>:
> Hi there,
> We have conducted an experiments for five years. The experiment is a
> completed block design with repeated measures. In detail, there is only one
> factor, i.e., temperature, and the experiments is performed in four blocks.
> In each block, the plot was split into two subplots. One subplot received
> two degree warming in Spring, and one degree warming in Fall, the other
> subplot didn't received any changes in Spring and Fall. We measured SOC
> every Spring and Fall. So we have got data something like:
> SOC, Temp, Season, Year, block
> 2.032, 2, Spring, 2007, 1
> 1.988, 0, Spring, 2007, 1
> 1.977, 1, Fall, 2007, 1
> 1.881, 0, Fall, 2007, 1
> It seems that mixed model might be the right way to analyze the data.
> However, we have encountered the difficulties that Temp seems to be nested
> with Season, and don't know how to code a formula for lme() in nlme package.
> Any suggestions or comments will be really appreciated. Thanks in advance.
> Best regards,
> R-sig-mixed-models op r-project.org mailing list
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