In other words, there were strict bans and they had only modest effects, including relative to the less strict bans. On p.34, Figure 2, you will see that 200 schools had strict bans, somewhat less than half the total (not every case is easy to classify). Note also that if smart phone bans could help with mental health problems in a big way, we still should see a change in mental health diagnoses, following the bans, yet we do not.