Linear time trend

[Laura Montolio]

Dear all,

I have data on the 2nd quarter from 1999 to 2008.I want to create a linear time trend, I tried with gen Trend=_n but I´m not sure if it is right.

Thanks!

[Dick Campbell]

Assuming your data are sorted in year order, that will work.

[Phil Bromiley]

This works if your data are ordered by year and quarter. It also assumes what you label Trend is a variable in your data set.

[Laura Montolio]

I do not have any trend variable in my dataset, just a variable that indicates the year and a variable that refers to 2nd quarter. Thus, do you mean that if I create a trend like that it will be wrong?

[Maarten Buis]

Might be, might not be: it depends on the sort order of your data. In general I would consider relying on the sort order a rather unsafe way of creating such variables (what if you have two or more observations in the same year/quarter?) Instead I would just create a Stata time variable. Say your year variable is called year and your quarter variable is called quarter, then you could type gen time = yq(year, quarter). You can make the data look prettier by following that with the command format time %tq. For more see help datetime.

[Laura Montolio]

Ok, I´m very grateful for your comment.