Dear friends,
I am wondering on how to implement the following statistical model and
would appreciate some feedback from some of you.
My question is whether the density of regenerants of the dominant conifer
Araucaria angustifolia depends on life stage (five levels) and management
history (three levels). Data consists on plant densities per one-hectare plot,
with eleven plots. To do the analysis, I fractioned the data on plant densities
per 0,01 hectare subplots (N = 1100).
Note that management history and life stage are crossed. I perceive this
as a two-way ANOVA
SQRT_DENSITY = CONSTANT + STAGE + HISTORY + STAGE*HISTORY
However, since each one-hectare plot is an observational unit rather than
a true experimental one, I think that plot identity should be considered or
controlled for in the analysis, because each plot has its own particular and
unknown history and other potential confounding factors.
The questions are:
1 - How to consider it in the above model. My current opinion is
SQRT_DENSITY = CONSTANT + STAGE + HISTORY + PLOT + STAGE*HISTORY
Where plot would mean plot identity.
2 - What do you think of the whole approach?
I would really appreciate from hearing your point of view on this small
matter!
Best whishes,
Alexandre
Dr. Alexandre F. Souza
Programa de Pós-Graduação em Biologia: Diversidade e Manejo da Vida Silvestre
Universidade do Vale do Rio dos Sinos (UNISINOS)
Av. UNISINOS 950 - C.P. 275, São Leopoldo 93022-000, RS - Brasil
Telefone: (051)3590-8477 ramal 1263
Skype: alexfadigas
[EMAIL PROTECTED]
http://www.unisinos.br/laboratorios/lecopop
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