This seems to be very difficult information to gather. Colleges report this (maybe it is 5-year graduation rates). Is there a way that we can get these figures on revisit days?
How many entering 9th graders end up graduating from that school. When I visited Exeter in the summer, they had 2 graduating class photographs on display in the bookstore: 1) everyone who graduated and 2) everyone who graduated who also came in 4 years earlier. It was considered unusual enough for them to have their own picture (maybe 1/2-3/4 of the class)
This seems like a much higher attrition rate over the course of 4 years than what is discussed in previous threads in years past.
I have seen that, too, at some schools, where 4 year seniors get special acknowledgement. While there is certainly some attrition, a big factor here is that many schools deliberately have a smaller 9th grade class, planning on adding a certain number in each subsequent year.
What @BlairParent says. They have statistics for how many are accepted to each grade level. So, theoretically, you could hunt around to find out how many were accepted each year (Year X # accepted to 9th; year X+1, number accepted to 10th; year X+3, number accepted to 11th; year X+4, number accepted to 12th + PG). From that count, subtract the number who graduated. (if you wind up with a negative number; well, just don’t end up with a negative number!) The rest represent attrition, early graduation, or extended study (due to coming back from a leave, for example).
You may wish to do this for several cohorts to account for any outliers.
My kid’s sophomore class is about one-third larger than her freshman class was. And yes, many schools do the special graduation photo just for 4-year seniors.
Many, many schools have 4 year senior photos. Personally, I find that to be a tradition that is long overdue to be 86’d, since many schools expand their 10th grade class with JBS graduates.