# Social Sciences: Setting up equation for difference in differences with multiple treatment groups

The dataset I'm looking at is household energy consumption in a particular area. I'm looking to analyze the effect of interventions which were aimed to reduce energy consumption on particular times of day so that is the effect I'm trying to measure i.e how effective the intervention was.

I have data with 1 control group and 4 treatment groups - each of which differ from the other only marginally. For clarity, in this case the participants who are being studied are intimated of the event through different means - email, SMS etc.

I set up dummy variables for each of my treatment groups as group2, group3, group4 and group5 along with dummies for treatment and post which are named as such.

I just want to make sure that I'm setting up my regression equation correctly.

The equation I have is:

Dependant var. = Treatment + Post + (Group1 + Group2 + Group3 + Group4)*Post


where each of the interaction variables signify the treatments for each of my groups.

Also I'm considering two days of pre-treatment data for my analysis.

My treatment period only lasts for about 3 hours on a particular day so I have - 3 hours the day of and 3 hours for the two days before the event I'm trying to look at.

Any help would be appreciated!

• Are you sure you want "Post" in the denomerator of these quantities? Usually for these types of analyses, it's the outcome variable that's measured at baseline and again at followup (pre/post). Are you sure you are interested in a change from exposure and its relationship to the outcome (presumably measured at followup)? – AdamO Jul 16 '15 at 22:02
• I've tagged this post analysis since it concerns analysis of a specific dataset. See the wiki for suggestions on how to edit and improve this post. – AdamO Jul 16 '15 at 22:04
• @AdamO, I've modified the question. I didn't mean a denominator. Thanks for adding the analysis tag, I'll keep that in mind going forward. – Ashwin Shankar Jul 16 '15 at 22:07