Hi. I am working with paneldata.

I want to remove individuals who don't have a value for each year in the period, but also keeping those who always have zero value. I will try to illustrate:

ID year X
1 2010 0
1 2011 0
1 2012 0
2 2010 0.01
2 2011 0
2 2012 0.011
3 2010 0.01
3 2011 0.01
3 2012 0.011

I want to keep indivdiuals like number one here. This is to serve as a control group in my DD regression. I want to remove individual two because treatment is not stable over the years. And I want to keep individual 3, because treatment occours in every year.

All help is appreciated. Thank you!