do not calculate for the first id

[sasphd]

Hello, 

I want the program not calculate flux and age if it is the first secid. I write this but it does not work. it still calculate for the first secid. What is wrong with this if first.secid then call missing(flux, age);

thanks

 data ageyear;
 set inception;
Age = yrdif(Inception_date, sas_date,'Actual');
flux=(TNA-lag1(TNA)*(1+mret))/(lag1(TNA));
if first.secid then call missing(flux, age);

run;

[PaigeMiller]

The FIRST. construct in a SAS data step requires a BY statement.

Also, it's not 100% clear to me what your requirement is ... do you mean first record in the data set, or first record of a block of SECID? If it is first record in the data set use

if _n_=1 then ...

[sasphd]

I need to put the  first record of a block of SECID to missing value.

Thanks

[PaigeMiller · Accepted solution]

Then you need the BY statement.