The changing economy is wreaking minor havoc with school enrollment projections for the next five years.

Student enrollment on the Vineyard is now projected to remain roughly level through 2013, according to a recent report from the New England School Development Council (NESDEC).

The new report contradicts last year’s figures which pointed to a steady decade-long downward trend, and were used in mid-term budget planning by Martha’s Vineyard Regional High School principal Steven Nixon.

Vineyard schools superintendent Dr. James H. Weiss said the new enrollment numbers will figure in budget planning for next year.

“It’s important we build the budget on what we believe the trends are,” said Mr. Weiss.

In his recent budget presentation at a public hearing, high school principal Steven Nixon announced plans for a ten per cent school staff cut in the light of a projected enrollment decline.

NESDEC provides projections for the next decade — the second five years show a consistent drop in high school numbers, though Mr. Weiss cautioned against drawing any conclusions from the latest numbers.

“It’s a sheer guesstimate,” he said.

The research group provides an annual set of enrollment projections for schools as part of a membership package, for which the office of the superintendent pays $1,450 per year.

NESDEC director of planning Donald Kennedy, who developed the model for Vineyard schools, said two principal factors in predicting patterns are birth rates and fluctuating property values, or real estate turnover. He acknowledged enrollment projection is not an exact science.

“Obviously all of this is in flux,” he said. “Real estate is unpredictable. Who knows when the economy is going to turn around? No one can absolutely foretell with a crystal ball what’s going to happen. But we have done a lot of sets [of projections] and are fairly close. We were within one per cent of our predictions for the current school year at the high school.”

Explaining the predicted leveling of high school numbers, Mr. Kennedy pointed to the number of students expected to enter high school next year. He predicts the number of ninth graders in the fall will total around 205 (up on 186 this year) based on a current 8th grade Islandwide count of 220.

In the longer term, he added that kindergarten through sixth grade numbers will grow by approximately 100 students over the next decade.

Mr. Kennedy said he sent a letter of analysis with the figures, with advice on usage, to Mr. Weiss in January.

“You have to take everything with a grain of salt and every year there are minor shifts,” he said.

In other school news, the transition period for a controversial state assessment formula for the high school budget, which split Island towns when it was introduced two years ago, will stretch out for longer than anticipated due to state cutbacks, according to Mr. Weiss.

The latest iteration of the formula was accepted as written at a high school committee meeting Monday night. The formula means West Tisbury will pay $184,828 more and Tisbury $83,331 more than they would under the old regional assessment formula.

Provisional town assessments are as follows: Aquinnah, $324,068; Chilmark, $490,399; Edgartown, $3,256,32; Oak Bluffs, 3,298,182; Tisbury, $3,033,888; West Tisbury, $2,076,263.

Two years ago Oak Bluffs voters triggered the adoption of the state formula, which requires a unanimous vote of the district to be repealed. Oak Bluffs has benefitted from the change in formula.

Last summer the town of Tisbury initiated a class action lawsuit against the state Board of Education over the formula. Tisbury has paid more each year under the changed formula.

Tisbury officials met late last year with state attorneys and representatives of the board of education, but have not yet decided on any further action, according to town administrator John Bugbee. Oak Bluffs has also been named in the lawsuit, although no town officials were at the meeting, Mr. Bugbee said.

A high school assessment committee chaired by Tisbury finance committee member Jon Snyder broke up last summer with no answers on an alternative to the state formula.

The transition phase of the formula will ultimately give way to a permanent structure similar to the old regional formula. Several at the meetings felt that the unanimity required to make a change was too difficult to achieve — as symbolized by the absence of representation from Edgartown.

“They didn’t get anywhere,” said Mr. Weiss of the meetings. “Four out of six will vote for this, so we’re done. We tried our best.”

For the formula to move ahead in the transition phase, additional funding is required from state Chapter 70 money. But Chapter 70 will be level-funded for 2010, which means the formula will not progress in the coming year.

“Until they increase Chapter 70, the formula stays static,” said Mr. Weiss.