[R-sig-ME] mixed model for nested factor?

Thierry Onkelinx thierry.onkelinx at inbo.be
Mon May 8 20:35:29 CEST 2017

Dear Jinsong,

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.

Best regards,

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht

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,
> Jinsong
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> R-sig-mixed-models op r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models

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