Kathleen Cei photo

High school grads Charles Washington (left) and Tyshawn Cannon of New Haven

Tyshawn Cannon, looking proud in a maroon polyester cap and gown, graduated from Wilbur Cross High School in New Haven last Thursday. Four years ago, Cannon was one of 1,796 incoming ninth graders citywide. Only 1,000 of Cannon's classmates graduated last week.

Somewhere along the way nearly 800 of Cannon's classmates disappeared and missed giddy celebrations like the one at Wilbur Cross, where students embraced each other and girls clutched single red roses.

Cannon saw his class shrink over four years but he's not sure where those students went. The state of Connecticut doesn't know either. It doesn't track students, which makes it hard to know how many ninth graders actually graduate four years later.

If all 800 missing students dropped out, then New Haven had a measly 55 percent graduation rate this year. This year's official rate won't be available until next year, but 55 percent is a far cry from the mid-70s New Haven has been reporting to the state for the past few years.

No one knows if those missing students moved out-of-state, transferred to another district or dropped out. That's a problem, says New Haven Mayor John DeStefano.

"Right now we don't know what happened to the other 800 [students]," says DeStefano. "Let's take some ownership — 1,000 is not acceptable."

New Haven and other Connecticut school districts follow an antiquated formula to calculate graduation rates. Four years ago Gov. Jodi Rell signed a pact — with all 50 states — agreeing to change the way the country counts graduates. The current method "tends to inflate the graduation rate" according to the National Governors Association because it counts students who take longer than four years to graduate and students who graduate with a GED instead of a diploma. It doesn't count students who drop out or move without giving official notice. In other words, it's not very accurate.

Only about a third of states have made good on the pact, and Connecticut's not one of them. Connecticut promises to start in 2010.

The pact requires states to look at the number of students entering ninth grade and, four years later, how many receive diplomas. The state Department of Education has a new $6 million statewide data system that can track students from kindergarten through graduation, even if they transfer to another district. That would help clarify how many students actually graduate and what happens to them along the way. The data system should be in full use next school year.

"The most important measurement of a high school's success rate is the graduation rate, and it's one of the indicators we have the least confidence in," says Marc Magee of the education nonprofit ConnCAN.

Hartford schools began following the new model in 2007 — under a new reform-minded superintendent — and announced a brutally honest 29 percent graduation rate. The state's data for that same year says Hartford graduated 77 percent of its students.

The difference is astounding, and is similar to what's seen in comparisons done by EdWeek, a national nonprofit. EdWeek compares the number of students that enter ninth grade with how many graduate four years later, but EdWeek's numbers don't take into account students who transferred or moved. Still, in some cases, like West Haven and East Haven, the difference between the two numbers is more than 30 percent.

Even though Connecticut's Department of Education has promised to change its calculation methods — and is required to do so by the feds — the department's spokesman Tom Murphy knocks EdWeek's statistics: "Our number reflects more accurately the true graduation rate."

That graduation rate does not explain where New Haven's 800 missing students are.