Help with panel data and lag

[Matt Hewitson]

Gidday! Hope someone can help me.

I have created a lag in my panel data (strongly balanced) using the following command

gen BVpshare_L1= BVpshare[_n-1]

However, when I browse the data using

br companyid BVpshare BVpshare_L1

I get a lag of 1 year from the last panel (companyid ) in the first year of the next panel (companyid)

How do I ensure that the last year of data is not lagged to the first year of the next panel?

[Andrew Musau]

Easier and more accurate if you use Stata's panel data features:

xtset companyid year
gen BVpshare_L1= L.BVpshare

Otherwise, group by company and sort by year when generating the variable:

bys companyid (year): gen BVpshare_L1= BVpshare[_n-1]

Note that in the above, the previous year may not necessarily be the current year minus one if you have holes in the panels.

[Matt Hewitson]

Thank you Andrew! That has done the trick!