Help adding a dummy variable

[Klementina Koka]

I am working with longitudinal household data and am (very) stuck at creating a dummy variable that takes the value 1 if a woman is having a child in the following year (so first baby next year is the variable I want to create). Here is a description of the data, where HID is the household ID, PID is the personal ID, and mother ID is the PID of the mother of the person. Any help would be greatly appreciated.

year	HID	PID	Sex	Age	MotherID	First baby next year
2019	115	1151	F	30	.	1
2020	115	1151	F	31	.	0
2021	115	1151	F	32	.	0
2020	115	1152	M	1	1151	.
2021	115	1152	M	2	1151	.
2021	115	1153	F	1	1151	.

[Daniel Shin]

Try the following:

[CODE]
replace MotherID=PID // if MotherID==PID, cannot be child
sort MotherID year Age
gen baby_next_year=age[_n+1]==1 if PID==MotherID & MotherID==MotherID[_n+1] & PID!=PID[_n+1]
/CODE]

[Klementina Koka]

[QUOTE=Daniel Shin;n1701689]Try the following:

I did this:
MotherID=PID
sort MotherID year Age
gen baby_next_year=age[_n+1]==1 if PID==MotherID & MotherID==MotherID[_n+1] & PID!=PID[_n+1]

but it didn't work: motherID becomes PID and the baby_next_year remains empty.