This new command was suggested by Esteban J. Quiñones (@estebanjq).

There are many commands (estout, outreg, etc.) that can create neat tables from regressions. This command will target the diff-in-diff (or double difference) regression model only and create tables tailored for exactly this model specification.

We want the table be of the format shown in the mock-up below:

The command is expected to be specified on the following format:

ieddtable varlist, dummies(D T DT)

Where varlist is a list of outcome variables and D is the treatment dummy, T is the time dummy and DT is the interaction of the two. The command will test that the regression is valid in the sense that there is at least some observations in each group, that D * T actually equals DT and so fourth.

Only the last column showing the double difference mean will be taken from the diff-in-diff regression. The other four means will be taken from regular means calculated separately. The reason for this is that we want to allow the user to include fixed effects, control variables etc., and when that is used the intercept, D, T D*T dummy betas can no longer be used by themselves to calculate means in the four groups. We do not want the means in the four leftmost columns in the mock-up to be impacted by fixed effects and control variables as it can create odd values such as negative harvest etc. A note will be included at the bottom of the table when control variables or fixed effects are used, which will explain why the mean in the fifth column cannot be calculated from the first four when FE and control variables are used.

The command should also be able to display the number of observations and the variation for each group for each outcome variable in addition to only the mean as in the mock-up. We do not know yet what should be the default. The number of observations should also be possible to display at the bottom of the table for each group, and then the command will test that the number is the same for that group in all outcome variables.

• The table will be possible to export in CSV or in TeX.
• The default labels in the table will be those in the mock-up, but all of them should be possible to specify manually.
• The variable labels for the outcome variables should be possible to set to varname, var label or to be specified manually.
• We have not decided yet if we want stars in a separate column.
• Star intervals should be possible to set manually.

This is just a first draft of the specifications for this command. Please comment blow if you have any additional options you want us to include.