Hi all,

I'm currently an undergraduate student and very new to STATA, I apologize for any "stupid" questions ahead of time.

For my model, I want to look at the effect of carbon pricing systems on GHG emission intensity.

I would like to construct a difference-in-difference model by comparing Canadian provinces who have different carbon pricing systems (carbon tax, cap-n-trade, nothing), and see the effect of these carbon pricing systems.

Where "time" is a dummy variable indicating the year that the carbon pricing system went into effect and "treated" represents a province that has a carbon pricing system. I saw a tutorial online to generate a "did" variable by time*treatment. Then regressing oilgas time treated did.

However, evidently my "did" variable carries the same values as my "time" variable, so it was omitted due to collinearity.

When I did the diff command, I got these results. How should I interpret this:

I'm just wondering if my approach is even correct and what I can do to make this model work.

Again, I apologize if my question is too general and vague. I'd appreciate it so much if I could get as much detail as possible!

Thank you, everyone!!

I'm currently an undergraduate student and very new to STATA, I apologize for any "stupid" questions ahead of time.

For my model, I want to look at the effect of carbon pricing systems on GHG emission intensity.

I would like to construct a difference-in-difference model by comparing Canadian provinces who have different carbon pricing systems (carbon tax, cap-n-trade, nothing), and see the effect of these carbon pricing systems.

Where "time" is a dummy variable indicating the year that the carbon pricing system went into effect and "treated" represents a province that has a carbon pricing system. I saw a tutorial online to generate a "did" variable by time*treatment. Then regressing oilgas time treated did.

However, evidently my "did" variable carries the same values as my "time" variable, so it was omitted due to collinearity.

When I did the diff command, I got these results. How should I interpret this:

I'm just wondering if my approach is even correct and what I can do to make this model work.

Again, I apologize if my question is too general and vague. I'd appreciate it so much if I could get as much detail as possible!

Thank you, everyone!!

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