Regression with a time trend

[Xavier Ochoa]

Hello everybody, I´m using Stata 18, and I'm trying to make a regression with a time trend analysis. Could someone help me and tell me what is the command or code to make this analysis? I've founded this example, and I tried to introduce the code as there, but it throws me "error" or "unrecognized". Please, could someone tell me the correct code or command to make this analysis? Thanks.

[Carlo Lazzaro]

Xavier:
without more details about the error you received from Stata and an excerpt of your dataset (see -dataex-), the following reply is based on my guess-work.
Usually, when time is considered as a continous variable (see -fvvvarlist- notation), it is frequent to search from a turning point (that is, a non-linear relationship between time and the regressand, that may have a minimum or a maximum).
If this is what you're after, you can code:

reg l_emp minimum_wage c.time##c.time

Otherwise, you can interact -miminum_wage- with -time-:

reg l_emp c.minimum_wage##c.time