Access and save estimates after xlincom

[Valentina Rutigliano]

Dear Statalist,

I am trying to run a linear regression, estimate the standard error of the sum of two coefficients via xlincom, and save the standard error as a separate variable.
My code is as follows:

sysuse auto2, clear
ssc install xlincom
reg price i.rep78##c.weight, coefl
g var=0
foreach x of numlist 2(1)5{
    xlincom name`x' = _b[`x'.rep78] + _b[`x'.rep78#c.weight], repost
    replace var=_se[name`x'] if rep78 == `x'
}

It produces the error

[name2] not found

even though I can see from matrix list e(b) that name2 is, in fact, stored in e(b).
I'm really puzzled as to why I get the error.
Any lead about how to solve this problem, or a different approach would be appreciated.
Thank you,

Valentina

[Leonardo Guizzetti]

If you are using the -repost- option, then -xlincom- adds the estimation results to the prior estimation results. You can inspect those results using

eret list
matlist e(b)

Your results will then be prefixed by "xlincom:", as if it was another equation in your model. So you can access them for example as

di _b[xlincom:name2], _se[xlincom:name2]

If however you use the -post- option of -xlincom-, there is no need for the "xlincom:' prefix.

di _b[name2], _se[name2]

[Valentina Rutigliano]

Thanks a lot Leonardo! Indeed using [xlincom:name2] solved the problem.