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smooth.spline error while fitting bacterial growth curves with grofit

1. Very likely, you have insufficient data in some of your growth
curves to do the fits using gcv. If  you remove the curves where the
bacteria didn't grow, things should work. Alternatively, there may
well be ways of expressing the model that would allow pooling across
cultures that didn't grow. (Sounds like a mixtures problem, actually:
you are mixing cultures that grow  with those that don't and need to
determine the mixing proportion and the growth parameters of those
that grew).

2. HOWEVER, IF you remove the curves, you may very well be getting the
wrong (biased) results -- i.e. your results will be irreproducible
garbage, as you will only be taking data from cultures that grew well.
I would **strongly** suggest you work with a local statistical expert
to help you deal with these issues. I do not think you should trust
remote advice from the internet on such complex data (including mine!)

Cheers,
Bert


Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
Clifford Stoll




On Sun, May 17, 2015 at 10:42 AM, Jeffrey David Johnson
<jefdaj at berkeley.edu> wrote: