Unrendered equation in chapter 4

Hi,

Thanks for this wonderful handbook!

In chapter 4 (see link to line in the Rmd file below), the closing bracket for \psi{} is missing:

Line 575 in 7001319

\psi_{\text{ATE} &= \E_0(Y(1) - Y(0)) \\ \nonumber

Screenshot below of this link: https://tlverse.org/tlverse-handbook/roadmap.html#missingness

Thank you for your kind words about our book, and we're glad you've found it to be a helpful resource. The typo you spotted has been addressed in #31, which should be merged soon; thanks for helping us catch this.

Happy to have helped!