Dear co-listers,
In an experiment a test product at a certain dose has been administered to
a set of units and, after some time, another dose has been tested to the
same units. The process has been repeated two more times, so we have data
on 4 dose. I do not have access to the original data. The only results I
have are the means, SD and N's for each dose. No data are available on
correlation.
Now the investigator needs to calculate the quotient of the data sets
(dose2/dose1, dose3/dose1 and dose4/dose1), and to summarize the results
by the mean and DS. I know that this can be done directly with the means,
but I'm almost sure that this is not the case with SD. Am I right? Or is
there any method to compute the SD of the quotient of two variables?
Thanks in advance
Frederic
Frederic Villamayor, BS
Researcher/Study Manager
Biostatistics Unit/Toxicology & Safety Pharmacology Dept.
CIDF Ferrer Grupo. C/ Juan de Sada, 32
08028 Barcelona (Spain)
Tel +34 935 093 236
Fax +34 934 112 764
[hidden email]
http://www.ferrergrupo.com
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