Hello!

I'm looking to run my first diff-in-diff regression for my research project that talks about the effects of supply deregulation on oil prices. My control group is obviously the states that didn't undergo supply deregulation, and my treatment group is the group of states that did. I will then analyze the effects on gas prices sold to consumers to determine if supply deregulation increased or decreased prices. I've already seen that all of the DD assumptions check out; ie parallel trends, etc.

However, there's a couple issues that I can't seem to get over when setting up for a DD regression:

Different states deregulated at different times, so I should definitely run different regressions for those states at those different years. However, should I pair up the US states on a one-to-one basis at those respective years(ie pair up Michigan which deregulated in 2008 and Nevada which hasn't undergone any deregulation and analyze prices since then), run each individual treated state against the mean price of the aggregate control group, or is there something else I should do?

I understand the basis of a DD regression, but I'm just confused as to the scope of my control and treatment groups. Any and all advice would be sincerely appreciated.