diet treatment model

#1
Hi all
I have an experiment for growth with fishes and diet treatment´s in
differents tanks... I have differents diets (8) in 24 tanks, each diet in
triplicated, i want determinated the tanks and diet effects. I had use
genstat and spss for calculate them, but i have some comfussion how calculate
diet effect resting tank effect because i can not use tank as block for diet
treatment, i think that maybe diet.tank interaction???
I had calculate effect treatment: tank and diet, separatedly and have significants differences, but when put both effects join i don have signifficant differences in diet...
someone could me help please?
Regards
 
#4
ok sorry, my english is not good...
I have to evaluate 8 differents diets replicated in 3 tanks each one (total= 24 tanks), i want determinated the significance of tanks and diet effects (as fixed effects), i want to know if i can subtract the tank effect to the treatment diet in a anova analysis,
i have tried with tanks nested in diet treatments, but i d like know if exist one way to substract the tank effect to diet treatament...
I had run the anova analysis with tank and diet, separatedly and have significants differences, but when run one anova with both effects in just one anova i dont found signifficant differences in diet treatments...
 
#6
Hi Dason,
I did read that thank effect could give "noise" in some statistical-genetic analysis...variability of the model could be affected by tanks.
Anyway diets treatments and performance of fishes could be affected by tanks this is a fact, therefore diet treatments analysis is affected by tanks...i should use a nested or interaction analysis?
Thanks
 
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Dason

Ambassador to the humans
#7
Yes it could be affected by tanks. But there isn't enough data to estimate the tank effect. It just gets confounded with the random noise term in the anova.
 
#8
ok, thank, in other way, is normal that when i calculate effect treatment: tank and diet like fixed effect, in separated anova, resulting that both effects have significants differences, but when run one anova analysis with both effects fixed in the same analysis i did not found signifficant differences in diet, its normal??..
 
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