getting the standard error for the difference between two means

[lesnorias]

Hi,

I have the means of two variables, together with the sample size and the standard eroor. I want to compute the difference between the two means (this is easy!) but also get the standard error for the diffrence. Do you know how to program this?
Thanks

 

[Jerry W. Lewis]

Insufficient information. Are you willing to assume that the variables
are independent? If not, do you have an estimate of the covariance?
Are you willing to assume that individual observation on each variable
have the same variance?

Jerry

 

[lesnorias]

Ok, here are the 2 variables:
infection rate in a population aged 18-29 in 1990
infection rate in the population aged 18-29 in the same area in 2001 (same area, but not same people given the way the age groups have been designed).
the sample is 50% larger in 2001.

Thanks,