st: error: variable present in model more than once when using -svy: reg- with replicate weights

["Brent Fulton" <fultonb@berkeley.edu>]

I am using Stata 9 -svy: reg- with JK2 replicate weights and get the
following error:

svyset [pw=wgt0], jkrweight(wgt1-wgt90, multiplier(1)) vce(jackknife) mse
svy: reg dep1 x1 x2 x3 x4 x1_x4
*where x1_x4 is x1 interacted with x4

error statement: x1_x4 present in model more than once 


I think the problem is with the replicate weights because the following
commands estimate the model (but obviously have incorrect SEs (and biased
parameter estimates in the first case)).
reg dep1 x1 x2 x3 x4 x1_x4

svyset [pw=wgt0]
svy: reg dep1 x1 x2 x3 x4 x1_x4

Any suggestions would be appreciated.

-Brent Fulton



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