Dear Everybody,
I am a researcher working in ecology. I work on prey-predator
relationship. I am finding it difficult to differentiate between Type II
and Type III functional responses. I have seen references where a logistic
regression model was used. This model is used only to determine the shape
of functional response by taking into consideration the proportion of prey
eaten (Na/No) as a function of prey offered (No). The data needs to fitted
to a polynomial function that describes the relationship between Na / No
and No:
Na/No=exp (Po + P1No + P2No2 + P3No3)/1 + exp (Po + P1No + P2No2 + P3No3)
I need to figure out the parameters estimates Po, P1, P2, and P3 using the
method of maximum likelihood.
Could anyone kindly help me to do this in SPSS? I need to know how to
structure the data (prey eaten, and prey offered)for the logistic
regression and what steps to follow in SPSS? There are references where
SPSS was used for this analysis.
(
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WBP-4T7088Y-2-5&_cdi=6716&_user=4019097&_orig=search&_coverDate=11%2F30%
2F2008&_sk=999529997&view=c&wchp=dGLbVtb-
zSkzS&md5=7c6c689dabd27b19819e98372baf4143&ie=/sdarticle.pdf)
Here is another link where similar data was structured for analysis in
SAS (
http://www.oup-usa.org/sc/0195131878/c10_data_ex1.html).
Thank you for your help
Nabaneeta Saha
Researcher
Ecology Unit.
University of Calcutta
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