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st: means when one variable has associated uncertainty


From   rmhaemh@ucl.ac.uk
To   statalist@hsphsun2.harvard.edu
Subject   st: means when one variable has associated uncertainty
Date   Wed, 10 Mar 2004 08:17:15 +0000

Dear All,
This may well have a very simple answer, but I haven't come across it in my field before. I have one variable which is measured on one occasion with certainty for every individual in a study, and another variable which is not known precisely for most individuals, but for which there are probabilities of the different possibilities assigned.
i.e.
studynumber var1 var2 probability of var2
1 9.8 a 0.5
1 9.8 b 0.25
1 9.8 c 0.25
2 5.7 a 0.75
2 5.7 c 0.25
3 4.9 a 1.0
etc...
e.g. for studynumber 2, variable 1 was measured as 5.7, and variable 2 may be "a" w.p. 3/4 or "c" w.p. 1/4
I want to calculate an unbiased estimate of the mean and sd for variable 1 by variable2 (considering information from all individuals) and also calculate whether or not the null hypothesis that var1 doesn't differ by var2 can be rejected.
Any help would be greatly appreciated,
Many thanks
Emma Hawe

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