Hi

I am working with a panel data set with c300 firms from years 2008 to 2014, with several firm-level variables such as sales, cash flow etc

I would like to rank firms by their sales in 2010 and then sort firms into categories (large and small) based on the value of sales in the year 2010. ie. if the firm's value for sales is in the top half/third/quartile in the year 2010, it takes the value one (large), and zero otherwise (small).

In short, I'm looking to identify large firms by looking at the top quartile/third/half of sales in 2010, and classify remaining firms as small.

Any questions or if something isn't clear, please ask, and thanks in advance,
Paul