The Graduation Rate vs. the Adjusted Graduation Rate

In the State of the Schools Address published on the Lynn Public Schools website, graduation rates are listed in terms of the four year adjusted rate; Lynn's four year adjusted graduation rate in 2011 was 71.9%. However, here we see the 'graduation rate' for Lynn listed as 68.6%. So which statistic is correct and what is the difference?

The Massachusetts Department of Elementary and Secondary Education (DESE) states that the 4 year graduation rate is the number of students who graduate in four years or less divided by the number of students beginning 9th grade together minus transfers out/deaths, plus transfers in (# of students graduating in 4 years or less/[# of first time entering 9th graders]- transfers out/death + transfers in). The adjusted 4 year graduation rate is the number of students graduating in 4 years or less divided by the number of students starting 9th grade together minus transfers out (# of students graduating in 4 years or less/[# of first time entering 9th grader] - transfers out/death). Thus the difference is that the 4 year graduation rate includes students who may not have started in a particular school or district but transferred into that school or district at some point during high school. On the other hand, the adjusted rate takes into account students who left a school or district but not those who may have entered after the 9th grade. In the case of Lynn, if one were to include students who transferred into the district and subtract those who either left or passed away, the graduation rate is 68.6%; the graduation rate  for students entering 9th grade at the same time and remaining within the Lynn public school district during the entire high school period is 71.9%.

Below is the graduation and adjusted graduation rates for the urban districts in Massachusetts. The cohort (or number of students included in the calculation) is also indicated.

	4 Yr Grad Rate	Cohort	4 Yr. Adjusted Grad Rate	Adjusted Cohort
Boston	64.4%	4632	69.4%	3543
Brockton	69.4%	1205	74.8%	907
Fall River	71.0%	624	76.6%	495
Holyoke	49.5%	491	51.7%	418
Lawrence	52.3%	905	54.2%	670
Lowell	69.6%	833	74.5%	646
Lynn	68.6%	1097	71.9%	923
New Bedford	56.4%	730	59.7%	566
Springfield	52.1%	1817	54.4%	1510
Worcester	72.0%	1853	75.1%	1541

*All Data Taken from: www.doe.mass.edu