Fetch former fails
fetch_former_fails.Rd
Given a session this fetches students that have failed 50% or more of their subjects
in the previous 1 - 3 sessions. This function collects the session results together, based
on n_prior_sessions
. So if n_prior_sessions == 2
, then it looks at the results in the
two prior major sessions (30, 60, 90) together.