I am not great with statistics so please be understanding. I have 17 pollinator sites that I collected data from and am comparing the effect of habitat type (2 classes) on several different response variables. Initially, I set up the model is SAS using PROC GLM as such;
proc glm data= gardens;
class Habitat;
model polldiver= habitat;
OUTPUT OUT=RESIDS R=RES;
Run;
PROC UNIVARIATE DATA=RESIDS NORMAL PLOT;
VAR RES;
RUN;
I am told that I need to add "site" as a random effect. However, I am unsure how to go about this.
My predictor variable is habitat type: urban or rural
My response variables are: pollinator richness, abundance, visits per flower, proportion of bombus, proportion of other bees, proportion of lepidopteran, proportion of other insects.
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Your habitats are the fixed replicates and the sites are subsamples
In the code, add "random site" below model. It adds site as a random effect to the model. I imagine that site would be a categorical variable, so you will also have to add site to the class statement in the code.
Ex:
proc glm data= gardens;
class Habitat site;
model polldiver= habitat;
random site;
OUTPUT OUT=RESIDS R=RES;
Run;
Awwwwww!!!! Yes! Thanks Amber! I forgot I had to name site in the class statement. Once again, you're the best! I hope your semester is going well!
OK. So it looks like I also need to include site in the model statement.
My code now looks like this:
proc glm data= gardens;
class Habitat Site;
model polldiver= habitat site;
Random site;
OUTPUT OUT=RESIDS R=RES;
Run;
PROC UNIVARIATE DATA=RESIDS NORMAL PLOT;
VAR RES;
RUN;
Do I also need to include the interaction between site and habitat in the model? e.g. Model polldiver=habitat site habitat*site
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