lead operators

[Adrienne Wold]

Hi,
I am trying to create a variable using a lead operator for data that is a monthly panel. The variable I am trying to get the lead for is measured at the yearly level though. To get the first and second leads, I am using the following code:

xtset id mdate
set more off
foreach var of varlist var1 var2 {
    g first`var' = `var'==0 & F12.`var'==1 if F12.`var'!=.
    g second`var' = `var'==0 & F24.`var'==0 & F24.`var'==1 if F24.`var'!=. & F24.`var'!=.
}

Is this the best/most efficient approach to create this operator?

[Clyde Schechter]

Never mind efficiency, let's get it correct first. Your -g second`var'...- command can't be right. Since it includes F24.`var' == 0 & F24.`var' == 1, you will always get 0 for second`var' (except where it will be missing), because F24.`var' can never be both 0 and 1.

Since I don't know what you intended to do for second`var', I can't specify how to correct this.

[Adrienne Wold]

Sorry, it should be:

 xtset id mdate set more off foreach var of varlist var1 var2 {    
g first`var' = `var'==0 & F12.`var'==1 if F12.`var'!=.    
g second`var' = `var'==0 & F12.`var'==0 & F24.`var'==1 if F24.`var'!=. & F24.`var'!=. }

For the second var, I'm trying to code the variable as one if if the two year lead of the variable is one and the 1-year lead and variable itself are both 0.

[Clyde Schechter]

gen second_`var'= F24.`var' == 1 & F12.`var' == 0 & `var' == 0 if !missing(`var', F12.`var', F24.`var')

should do it.

[Adrienne Wold]

Thanks. Although I should be using 13 and 26 instead?

[Clyde Schechter]

No. If you have monthly data and you want to look 1 and 2 years ahead, then you look at F12. and F24., respectively.