Post-treatment bias clarity

[ASKurz]

In Section 5.3.3, define the h0 variable before the treatment and fungus variables in the d data frame. This should help clarify the temporal sequence. Somewhere in the prose, you might also mention this follows an example from Cochran (1957, Section 2.3; https://doi.org/10.2307/2527916), which was also discussed in Rosenbaum (1984, Section 3.3; https://doi.org/10.2307/2981697).