I think my question is pretty straightforward. I'd like to know what my "Group" is for a difference in differences analysis.

Study: Newspaper articles from 1985-2017 were categorized as either in favor, against, or neutral toward a specific topic. These are weighted and graphed.

Array


There is a clear divergence between the Favor and Against variables that happen roughly around 2007 or 2008. I would like to test this using a treatment variable defined as "before 2008" and "2008 and on," Treatment 0/1. The time is Year. I've added "the mean of the Favor and Against variables" for the control variable, Control.

This is a mock-up of my data:

Array

The unit of analysis is newspapers for each year.
But what's up with the Group? I know it's supposed to be categorical ... but what am I supposed to put?

The syntax I have for the command is didregress (Favor) (Treatment), group(?????) time(Year)
Any thoughts on what my Group should be?
Thank you!