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st: testing for significant differences between independent samples using svytab


From   Lacey Hartman <[email protected]>
To   [email protected]
Subject   st: testing for significant differences between independent samples using svytab
Date   Mon, 28 Jan 2008 13:43:04 -0600

I am wondering why I get different results when using these 2 approaches to testing for a significant difference between two independent samples.  I am also wondering which approach is more accurate and why.

#1 compare confidence intervals generated from svytab row obs ci se
I find that the confidence intervals overlap 

#2 
test for significant difference using the following  t-test for independent samples:

value2-value1/ square root of (standard error of value 1 ^2 +standard error of value 2^2)

this formula gets me to a value of 2.12, significant at the 95% level

Again, why is there a difference and which approach is more correct?

Thanks!

Lacey Hartman
Senior Research Scientist
Health Economics Program
MN Department of Health
tel: 651-201-3556
fax: 651-201-5179
[email protected]






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