Issue on page /01-Introduction-To-Causality.html

[tacla]

After the following "...and we have that the causal impact on the treated is the same as in the untreated (because they are very similar)":

I do not understand why you write E[Y|T=0] since we don't have E[Y1|T=0] in the above lines.

[dwanev]

I think the author is saying these lines are all equal. The second term of the of the last 2 lines is saying "the expected value of Y given they did not get the treatment", it is just the notation that is changing.