I've been thinking again about why spam emails have errors in them. Here's one story I find appealing, realized as a fun combination of instrumental variables, one-sided non-compliance, and the pursuit of the biggest LATE.
@conjugateprior this is the story i’d heard and was convinced by, too
@mikarv whether true or not it certainly provided a nice teaching example of when LATE is very much not ATE (or ATT in this case).