K N and P J Harris ecoli at
Wed Aug 23 03:09:46 EST 1995

For these awkward little beggars Peter Herman is quite right.
BUT, before you launch out onto a survey take a look at the confidence 
intervals for MPN methods. They give a number, OK, but the +/- intervals 
are horrific unless you want to do huge numbers of replicates per 
dilution. There are computer programmes which allow you to get MPNs from 
virtually any combination of dilutions and replicates.
To get really good numbers it is worth thinking about multiwell plates 
and some degree of automation. We had to get into this for soil 
protozoan numbers some time ago.
Otherwise it might be necessary to find an external examiner/assessor 
who does not believe in statistics !
Best of luck,
Peter Harris,
University of Reading, Soil Science Dept.
AKA P.J.Harris

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