[R] Predicted values for zero-inflated Poisson

Alain Zuur
Mon, 09 Jul 2012 19:00:10 -0000

Lee, Laura wrote
>
> Hi all-
>
> I fit a zero-inflated Poisson model to model bycatch rates using an offset
> term for effort. I need to apply the fitted model to a datasets of varying
> levels of effort to predict the associated levels of bycatch. I am seeking
> assistance as to the correct way to code this.
>
>
> ---
> Just use the function zeroinfl from the pscl package...fit your
> model...extract the estimated parameters, specify a data frame with
> variables for which you want to make predictions (including values for
> your offset), use model.matrix to convert it into the correct format and
> calculate your fitted values.
>
> You can also use the function predict.
>
> You can either predict the binary (pi) and count parts (mu), or the
> predicted values for the ZIP ((1-pi)*mu)..or better...both.
>
>
> For detailed examples and code see:
>
> Zero Inflated Models and Generalized Linear Mixed Models with R. (2012)
> Zuur, Saveliev, Ieno.
>
> http://www.highstat.com/book4.htm
>
>
> Alain
>
> --
>
> Dr. Alain F. Zuur
> First author of:
>
> 1. Analysing Ecological Data (2007).
> Zuur, AF, Ieno, EN and Smith, GM. Springer. 680 p.
> URL: www.springer.com/0-387-45967-7
>
>
> 2. Mixed effects models and extensions in ecology with R. (2009).
> Zuur, AF, Ieno, EN, Walker, N, Saveliev, AA, and Smith, GM. Springer.
> http://www.springer.com/life+sci/ecology/book/978-0-387-87457-9
>
>
> 3. A Beginner's Guide to R (2009).
> Zuur, AF, Ieno, EN, Meesters, EHWG. Springer
> http://www.springer.com/statistics/computational/book/978-0-387-93836-3
>
>
> 4. Zero Inflated Models and Generalized Linear Mixed Models with R. (2012)
> Zuur, Saveliev, Ieno.
> http://www.highstat.com/book4.htm
>
> Other books: http://www.highstat.com/books.htm
>
>
> Statistical consultancy, courses, data analysis and software
> Highland Statistics Ltd.
> 6 Laverock road
> UK - AB41 6FN Newburgh
> Tel: 0044 1358 788177
> Email: highstat at highstat.com
> URL: www.highstat.com
> URL: www.brodgar.com
>
>
>
>
> Thanks in advance!
>
> Laura
>
>
>
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-----
Dr. Alain F. Zuur
First author of:

1. Analysing Ecological Data (2007).
Zuur, AF, Ieno, EN and Smith, GM. Springer. 680 p.
URL: www.springer.com/0-387-45967-7


2. Mixed effects models and extensions in ecology with R. (2009).
Zuur, AF, Ieno, EN, Walker, N, Saveliev, AA, and Smith, GM. Springer.
http://www.springer.com/life+sci/ecology/book/978-0-387-87457-9


3. A Beginner's Guide to R (2009).
Zuur, AF, Ieno, EN, Meesters, EHWG. Springer
http://www.springer.com/statistics/computational/book/978-0-387-93836-3


Other books: http://www.highstat.com/books.htm


Statistical consultancy, courses, data analysis and software
Highland Statistics Ltd.
6 Laverock road
UK - AB41 6FN Newburgh
Tel: 0044 1358 788177
Email: highstat at highstat.com
URL: www.highstat.com
URL: www.brodgar.com


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