while possibly outside the domain of your original question, I suspect that
you may be able to treat your yield data as integers by treating the
denominator as an offset variable (as a technicality, I'd argue that, even
after dividing by a constant, your data remain discrete--just not
integers). this common technique would appear to take you back into the
discrete world that Nicholas touched on. brian
****************************************************************
Brian Gray
USGS Upper Midwest Environmental Sciences Center
575 Lester Avenue, Onalaska, WI 54650
ph 608-783-7550 ext 19, FAX 608-783-8058
[EMAIL PROTECTED]
*****************************************************************
Ernesto Jardim
<ernesto@ipimar. To: Nicholas Lewin-Koh
<[EMAIL PROTECTED]>
pt> cc: Mailing List AI-Geostats
<[EMAIL PROTECTED]>
Sent by: Subject: Re: AI-GEOSTATS: Log
transformation and zeros
ai-geostats-list
@unil.ch
10/02/2002 09:47
AM
Please respond
to Ernesto
Jardim
Hi
The data are not discrete. We collect number per hour, so it's a yield !
Thanks
EJ
On Wed, 2002-10-02 at 15:27, Nicholas Lewin-Koh wrote:
> Hi,
> If the data are counts, ie integer number of fish and not tons, you
> might want to try a discrete model such as a negative binomial or
> Poisson. I have listed some references below, the top two have a more
> Bayesian flavor.
>
> Nicholas
>
>
> Alexander, N., Moyeed, R., Stander, J. (2000). Spatial modelling of
> individual-level parasite counts using the negative binomial
> distribution, Biostatistics, 2000, 1, 453-463.
>
> Diggle, P. J., Moyeed, R. A., Tawn, J. A. (1998). Model-based
> geostatistics (with discussion), J. R. Statist. Soc. C, 47, 299-350.
>
> Gotway, C.A., Stroup, W.W. (1997) A Generalized Linear Model Approach
> to Spatial Data Analysis and Prediction. Journal of Agricultural, Bio-
> logical and Environmental Statistics 2(2), pp. 157�178.
>
>
> On Wed, 2002-10-02 at 19:24, Ernesto Jardim wrote:
> > Hi
> >
> > I'm analysing fisheries data (number of fish caught per hour) and I
have
> > some 0 values. When I log-trans I have to translate the values by
hading
> > some value.
> >
> > My question is which value is the best ? is there any works about this
?
> >
> > I usually had 1 so that I get values between 0 and infinite (no
negative
> > value) but I have doubts about it.
> >
> > Regards
> >
> > EJ
> >
> >
> >
> >
> > --
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