finding medians before and after an event year

[hikhieu]

Dear SAS community users,

I have an unbalanced panel data set with firm years. In that set, I have a dummy marking an event year (year when new stock is issued). I want to find the median of a variable (sale, for example) 3 years before the event year for each firm ID. Then I want to find the median of the same variable 5 years after the event year for each firm ID.

I'd appreciate any help here. Thank you in advance.

Regards,

Hinh

[Reeza]

Create a flag that identifies before and after.
Run a proc means with the flag as a grouping variable, either BY or CLASS.

Need more help? Please post more details, including sample data and expected output.

[PGStats]

Do it in one step with correlated sub-queries:

proc sql;
create table medianSales as
select 
    firm,
    (   select median(sales) 
        from have 
        where firm=a.firm and year between a.year-3 and a.year-1 )
        as medianSalesBefore,
    (   select median(sales) 
        from have 
        where firm=a.firm and year between a.year+1 and a.year+5 )
        as medianSalesAfter
from have as a
where flag;
select * from medianSales;
quit;

[Reeza]

If you have SAS 9.4 - median function not valid in PROC SQL in earlier versions.

It won't generate an error, but it won't be the metric you expect. 

[PGStats]

Thanks @Reeza. A good thing to know.

[hikhieu]

Thanks so much for your prompt help, PG and Reeza. I will try and let you know.