Dear R Help -
I am analyzing data from an ecological experiment and am having problems
with the ANOVA functions I've tried thus far. The experiment consists of a
blocked/split-plot design, with plant biomass as the response. The following
is an overview of the treatments applied (nitrogen addition, phosphorus
addition, and seeded/not seeded) and at what level (block, main-plot, and
sub-plot):
- 6 experimental blocks divided into 2 main-plots
- each main-plot divided into 8 sub-plots, for a total of 96 sub-plots (6
blocks * 2 main-plots * 8 sub-plots)
- 16 experimental treatment conditions in a 4 x 2 x 2 factorial design:
- N at 4 levels for each sub-plot
- P at 2 levels for each sub-plot
- Seed at two levels for each block (one level per main-plot)
- response variable = biomass
Block
Main Plot 0 : No Seed
Sub-Plot 0.1 : N0 P0
Sub-Plot 0.2 : N0 P1
Sub-Plot 0.3 : N1 P0
Sub-Plot 0.4 : N1 P1
Sub-Plot 0.5 : N2 P0
Sub-Plot 0.6 : N2 P1
Sub-Plot 0.7 : N3 P0
Sub-Plot 0.8 : N3 P1
Main Plot 1 : Seed
Sub-Plot 1.1 : N0 P0
Sub-Plot 1.2 : N0 P1
Sub-Plot 1.3 : N1 P0
Sub-Plot 1.4 : N1 P1
Sub-Plot 1.5 : N2 P0
Sub-Plot 1.6 : N2 P1
Sub-Plot 1.7 : N3 P0
Sub-Plot 1.8 : N3 P1
I've tried several different approaches to run an ANOVA (lmer, aov, lme) on
this data, trying to use type III SSs and include a random factor, but am
having problems. Any suggestions?
Thank you for your help!
-Mari Pesek
--
Dept of Ecology and Evolutionary Biology
University of Kansas
Haworth Hall, 1200 Sunnyside Ave
Lawrence, KS 66045
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