Darrell Huff’s “How to Lie with Statistics” was an instant classic following its publication in 1954. Although Huff’s intent was to promote a better understanding of statistics, many read only the title and concluded that reported statistics are routinely manipulated and can’t be trusted. In the original spirit of Huff’s book, however, Beaconomics will periodically explore what widely quoted figures on K-12 education can and can’t tell us. In this post we’ll focus on the graduation rate.
This is easy, right? If you start with 100 high schoolers and 75 get a diploma, the grad rate must be 75 percent.
Not so fast. The variation in reported graduation rates is mostly about starting and ending points. Are we asking what share of high school seniors graduate at the end of the year? That tells us something about the last year of high school but not much about the entire experience. We’re ignoring children who dropped out when they turned 17. For most urban schools, keeping older teens in school is a significant challenge.
If we are measuring the effectiveness of secondary education at a specific school, we want to know how many students graduate as a share of the number who enter. The standard measure is called the “four-year cohort of survival” method. The “population” (which becomes the denominator of the estimate) is the number of children who entered 9th grade. The number who graduated in four years is the numerator. The figure is adjusted for students who transfer in or out from another school.
Read more on the Rochester city schools: “Why charter schools are part of the solution”
The graduation rate reported for New York public schools for students graduating at the end of the 2016-17 school year is called the 2013 Cohort Graduation Rate, i.e. the share of students who entered in 2013-14 who graduated at the end of the 2016-17 school year.
If this isn’t complicated enough, the official statistics distinguish between June and August graduation. Rochester city schools’ 2013 cohort rate is 52 percent for June grads but rises to 57 percent if August grads are considered. Retaining students until they become seniors isn’t good enough—they still need to comply with state Regents graduation standards if they hope to graduate. Many students need the summer to nail down a missing course or Regents exam.
Some don’t make it by August, but don’t drop out. The state Education Department reports that 61 percent of students who entered in 2011-12 had graduated by the end of the 2016-17 academic year.
Just for the record, the 57 percent four-year (August) graduate rate is a marked improvement for Rochester. The average from 2010-2015 was 50 percent. The six-year graduation rate for students entering high school in 2011 was 61 percent.
The chart above captures the graduation rates for New York’s large urban school districts for three entering cohorts—2011, 2012 and 2013. Note that the Yonkers City School District has been doing something right as the four-year graduation rate for students entering in 2013 is higher than the six-year graduation rate for students entering in 2011.
Dropout rates also vary substantially by district. The dropout rate rises over time for the same cohort as students become discouraged and quit school. These figures do take into account students who complete a GED.
Rochester’s dropout rate rises from 22 percent for students in the 2013 cohort to 34 percent for students in the 2011 cohort.