DID models for non-panel data

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miharbi
Posts: 10
Joined: Mon Jun 06, 2016 5:39 pm

DID models for non-panel data

Hi everyone,

I found in the EViews Help this statement: (To estimate DID models on non-panel workfiles, you will need to specify the appropriate least squares model manually using standard least squares regression.)

What does this statement mean, especially for non-panel data structures? I hope to find a practical example of this point?

EViews Gareth
Fe ddaethom, fe welon, fe amcangyfrifon
Posts: 13369
Joined: Tue Sep 16, 2008 5:38 pm

Re: DID models for non-panel data

Difference in Difference estimation is just standard OLS. EViews doesn't have a built in DiD estimator for non-panel workfiles, but since it is just OLS, you can estimate it with the OLS estimator.

miharbi
Posts: 10
Joined: Mon Jun 06, 2016 5:39 pm

Re: DID models for non-panel data

Thank you Gareth for your response!

I have no problem with what you said, but I want to understand the structure of non-panel data. What do you mean by it? Is there a practical example or a paper that has addressed this?

startz
Non-normality and collinearity are NOT problems!
Posts: 3777
Joined: Wed Sep 17, 2008 2:25 pm

Re: DID models for non-panel data

Suppose you have an outcome variable y and two dummy variables, treated and after. (So some observations of y are treated after a certain date and others are never treated--the control group.) You could do

Code: Select all

ls y c treated after treated*after
The last coefficient is the DiD estimate.

miharbi
Posts: 10
Joined: Mon Jun 06, 2016 5:39 pm

Re: DID models for non-panel data

Thank you Starz,
It's very clear now.