Ch. 6 - typo

[WillTirone]

There is an issue on chapter 6, in the following paragraph

and \beta is the difference in means or the ATE in the case of random data

\beta = [Y_i | T_i = 1] - [Y_i | T_i = 0]

I believe this is just missing the expectation sign, I could also be misunderstanding :)

\beta = E[Y_i | T_i = 1] - E[Y_i | T_i = 0]