Hi Again,
I reran the updated code (as per Howie's suggestion, see below), and it
ran fine. However, when I first dropped all individuals where union ==.
the code failed at the last wave (12). Stata gave an error r(9777); which
has no help associated with it.
I think it has something with how it reads the last wave (12), because
when I set the code to run only through 11 waves it works fine. Again, all
help is welcome:
**** start code****
*webuse nlswork, clear
bysort idcode (year):gen wave = _n
tsset idcode wave
drop if union==.
logit union ln_wage age collgrad tenure hours if wave==`i'
predict ps1 if e(sample)
sum wave
local max = r(max)
forvalues i=2/`max' {
logit union l.ln_wage l.age l.collgrad l.tenure l.hours if wave==`i'
predict ps`i' if wave == `i'
}
egen psfinal = rowmax(ps*)
***** end code******
Date: Thu, 25 Jun 2009 16:44:26 -0400
From: Howard Lempel <[email protected]>
Subject: st: RE: Code erroring out because of "no observations"
Hi Ariel,
In your loop, _N represents the number of total observations, not the
total number of waves. There are only 15 waves of data, so when i gets to
16, you get an error - there are no observations for which wave==16.
I think you want to change your loop to the following:
forvalues i=2/15 {
logit union l.ln_wage l.age l.collgrad l.tenure l.hours if wave==`i'
predict pred`i' if wave == `i'
}
If you don't want to stick 15 in as a magic number, you could to the
following:
sum wave
local max = r(max)
forvalues i=2/`max' {
logit union l.ln_wage l.age l.collgrad l.tenure l.hours if wave==`i'
predict pred`i' if wave == `i'
}
Hope this helps.
Howie
From: Ariel Linden, DrPH [mailto:[email protected]]
Sent: Wednesday, June 24, 2009 2:40 PM
To: '[email protected]'
Subject: Code erroring out because of "no observations"
Hi All,
I am running some code in the nlswork file in which I use lagged values in
the present period’s logit model. Since there are individuals in the
file that don’t have more than one period (wave), the code errors with
“no observations.†As a result, the code cannot continue to the last
line I have below which generates a variable with the max of all the
waves.
I tried using “capture†but the loop never ends.
I’d appreciate it if someone could tell me how to override the error and
continue on to the next line of code? (if my poor coding could be improved
as well, I’d appreciate that as well) ☺
Thanks in advance
Ariel
***** start of code**********
webuse nlswork, clear
sort idcode year
bysort idcode: egen wave = seq()
tsset idcode wave
logit union age collgrad tenure hours if wave==1
predict pred1 if e(sample)
forvalues i=2/`=_N' {
logit union l.ln_wage l.age l.collgrad l.tenure l.hours if wave==`i'
predict pred`i' if wave == `i'
}
egen predfinal = rowmax( pred*)
***** end of code*************
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