individual covariates

questions concerning analysis/theory using program MARK

individual covariates

Postby annaren » Mon Jun 23, 2008 1:42 pm

Really sorry to post another question but I am having problems using individual covariates in my model. I have used habitat size as covariate as I am interested to see the effect of habitat size on survival as I hypothesise that those in small, narrow habitats have a lower survival.
When I look at the parameter estimates the following message is given at the top:

Following estimates based on unstandardized individual covariate values:
Variable Value
--------- -------------
VAR1 7.2390948

Does this mean that MARK simply is taking an average of the covaraites to give the estimates and is there a way to make it use all values in order to answer my question,i.e. does survival increase as margin width increases?
annaren
 
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Re: individual covariates

Postby cooch » Mon Jun 23, 2008 1:51 pm

annaren wrote:Really sorry to post another question but I am having problems using individual covariates in my model. I have used habitat size as covariate as I am interested to see the effect of habitat size on survival as I hypothesise that those in small, narrow habitats have a lower survival.
When I look at the parameter estimates the following message is given at the top:

Following estimates based on unstandardized individual covariate values:
Variable Value
--------- -------------
VAR1 7.2390948

Does this mean that MARK simply is taking an average of the covaraites to give the estimates and is there a way to make it use all values in order to answer my question,i.e. does survival increase as margin width increases?


First, parameter estimate - beta, or normal probability scale?

Second, what MARK reports (how, why, what you can change) in terms of parameter estimates for individual covariates, is covered in a fair bit of detail in current Chapter 11. If you haven't had a good look, take some time to read the chapter. If you have, start re-reading about midpoint on p. 12. Also, make sure you read section 11.5, which deals with visualizing the relationship between the parameter of interest and the covariate(s).
cooch
 
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Location: Cornell University


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