Hi there,

I have some difficulties dropping observations.

If the ID did not receive subsidy in all the months (2015m9 (668) up to 2016m8 (678)), I would like to drop them and if the ID received subsidy in ANY of the 12 months, I would like to keep all the observations for that ID.

so in the example below, I want to drop ID 1 but keep all the observations for ID 2.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(ID month subsidy)
1 668 0
1 669 0
1 670 0
1 671 0
1 672 0
1 673 0
1 674 0
1 675 0
1 676 0
1 677 0
1 678 0
1 679 0
2 668 1
2 669 1
2 670 0
2 671 0
2 672 0
2 673 0
2 674 0
2 674 1
2 675 1
2 676 1 
2 676 1
2 678 0
end
format %tm month

Thank you!