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st: RE: Multiple comparisons, non-normal data
To calculate confidence intervals for rank statistics in Stata, you can
use the -somersd- package, downloadable from SSC. To perform multiple
test procedures, you can use the -smileplot- package, also downloadable
from SSC. And I suspect that the -parmest- package (also downloadable
from SSC) would be useful in writing the confidence intervals and
P-values from -somersd- to a dataset which can then be input to
-smileplot- to carry out multiple-test procedures. To download add-on
packages from SSC, use the -ssc- command in Stata.
Apart from that, I cannot say much, as I do not know the details of your
project, eg numbers of individuals per tank or what kind of animals are
laying eggs and living in tanks.
I hope this helps.
Best wishes
Roger
Roger Newson
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: [email protected]
www.imperial.ac.uk/nhli/r.newson/
Opinions expressed are those of the author, not of the institution.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Knag
Anne-Christine
Sent: 24 May 2007 13:33
To: [email protected]
Subject: st: Multiple comparisons, non-normal data
Hi,
I have data on an experiment where 9 tanks were sampled every day for 3
months. One of the variables measured were fecundity. Relative fecundity
(fecundity at day n divided by total fecundity of the tank) is not
normally
distributed. Can someone please help me to figure out how I can compare
the
distribution of the fecundity between the 9 tanks?
Each of the nine tanks contains one group of individuals that have been
given either treatment C, L, M, H or E at time 1 or 2. I.e tank 9 is a
group
given treatment E at time 2, while tank 4 is a group given E at time 1.
There are no replicates of the treatment, but if there is no effect of
time
(1 or 2) given the treatment, I believe that I can use the tanks with
the
same treatment given at different times se as replicates of treatment.
In addition to have measured the fecundity (number of eggs produced), I
also
have the diameter of the eggs collected. I would like to know how the
diameter changes over time in each of the tanks and whether it differs
between the tanks.
I will be very, very grateful for any help that you can give me.
Thanks and have a nice day!
/Anne-Christine
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