Greetings to all --

As always, I am grateful for the help of the R community.  The generosity of
other R users never ceases to impress me.  Just to recap the responses I
have had to this question, in case they can help anyone else down the line:

Robert LaBudde suggested Applied Survey Data Analysis by Heeringa et al. as
a go-to reference

Ruben Roa suggested glm() with binomial family for modeling Listeria
presence/absence, glm() with Gamma family for modeling Listeria
concentrations, or the betareg() function of the betareg package for
modeling Listeria proportions.

Jim Lemon suggest the lme family of functions in the lme4 package, and Modern
Applied Statistics with S as a good reference (which, thankfully, I have in
my library).

Richard Weeks replied to the whole group suggesting sensory analysis with
the sensominer package.

Thanks again for your time, everyone.

Sarah


On Tue, Jul 13, 2010 at 3:07 AM, Richard Weeks
<rweeks@mango-solutions.com>wrote:

> Hi Sarah,
>
> We regularly undertake work in the food sector and have developed many
> custom built solutions. To be more specific, the statistics we employ is
> that of sensory analysis and we regularly use the sensominer package in
> R.
>
> Regards,
>
> Richard Weeks
>
> Mangosolutions
> data analysis that delivers
>
>
> Mail: rweeks@mango-solutions.com
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>
> -----Original Message-----
> From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org]
> On Behalf Of Sarah Henderson
> Sent: 12 July 2010 22:42
> To: R List
> Subject: [R] Question about food sampling analysis
>
> Greetings to all, and my apologies for a question that is mostly about
> statistics and secondarily about R.  I have just started a new job that
> (this week, apparently) requires statistical knowledge beyond my
> training
> (as an epidemiologist).
>
> The problem:
>
> - We have 57 food production facilities in three categories
> - Samples of 4-6 different foods were tested for listeria at each
> facility
> - I need to describe the presence of listeria in food (1) overall and
> (2) by
> facility category.
>
> I know that samples within each facility cannot be treated as
> independent,
> so I need an approach that accounts for (1) clustering within facilities
> and
> (2) the different number of samples taken at each facility.  If someone
> could kindly point me towards the right type of analysis for this and/or
> its
> associated R functions/packages, I would greatly appreciate it.
>
> Many thanks,
>
> Sarah
>
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