Text stimulus (timeline): Timeline titled 'Attendance before and after reminder texts.' Four monthly markers January, February, March, April. Center A line: 50, 52, 61, 66 attendees; labels identify above March 'Reminder texts begin.' Center B comparison line: 51, 54, 55, 56 attendees; labels identify 'No reminder change.' Y-axis from 45 to 70 attendees. What is the most careful policy conclusion?