reshape inside a bootstrap program

[dimitris karletsos]

Dear Statalist,

I need to use the reshape command inside a bootstrap program.

My question is: how can I run the reshape command inside the program?


WORKING EXAMPLE

sysuse auto, clear

gen bene_id = _n

capture program drop myboot

program define myboot, eclass

capture keep price weight length bene_id __000000 mpg

gen random_id = runiform()
sort random_id

replace length = length * 1.1 if random_id < 0.5

areg price weight length, absorb(mpg)

matrix temp = e(b)
ereturn post temp
end

bootstrap, reps(100) seed(200): myboot

NOT WORKING EXAMPLE (I add the reshape command)

sysuse auto, clear

gen bene_id = _n

capture program drop myboot

program define myboot, eclass

capture keep price weight length bene_id __000000 mpg

gen month_1 = 1
gen month_2 = 2
gen month_3 = 3
gen month_4 = 4
gen month_5 = 5
gen month_6 = 6

reshape long month_, i(bene_id) j(months)

gen random_id = runiform()
sort random_id

replace length = length * 1.1 if random_id < 0.5 & month_ <= 3

areg price weight length, absorb(mpg)

matrix temp = e(b)
ereturn post temp
end

bootstrap, reps(100) seed(200): myboot

The purpose of this code is solely to demonstrate the current issue I am facing in using the reshape command inside a program with a similar (not identical) structure. I cannot post the original because of its length.

So, I answer two obvious objections preemptively.
Q1) Do you know that, by reshaping and then sorting by random_id, each individual's observations will be sorted randomly, and so the 'working example' and the 'non working example' are two inherently different approaches? A1) Yes I know it, this is just a demo code.
Q2) Why don't you run the reshape command outside of the program? A2) I cannot, because what I am doing requires this to happen inside the bootstrap program (take my word on this).

So, my question is simply how can I run the reshape command inside the bootstrap program above, without getting this error message that I get:

Bootstrap replications (100)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx    50
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx   100
insufficient observations to compute bootstrap standard errors
no results will be saved

Thanks

[dimitris karletsos]

Hi people, I solved it. The answer to "how to use reshape inside a bootstrap program?" is "do not use reshape, use tolong instead".

God knows what was happening in the background in the reshape command that made my bootstrap program fail. If anyone else apart from God knows it, please post it below for knowledge sharing.

In the meantime, I post the working code with tolong.

sysuse auto, clear

gen bene_id = _n

capture program drop myboot

program define myboot, eclass

capture keep price weight length bene_id mpg __000000

gen month_1 = 1
gen month_2 = 2
gen month_3 = 3
gen month_4 = 4
gen month_5 = 5
gen month_6 = 6

tolong month_, i(bene_id) j(months)

gen random_id = runiform()
sort random_id

replace length = length * 1.1 if random_id < 0.5 <= 3 & month_ <= 3

areg price weight length, absorb(mpg)

matrix temp = e(b)
ereturn post temp

end

bootstrap, reps(100) seed(200): myboot