The cost allocation formula for the Up-Island Regional School District is substantially fair, according to a long-awaited independent analysis released yesterday.

Two years in the making, the financial analysis was commissioned by the three up-Island towns and authored by accounting consultant Mark D. Abrahams of Framingham. Mr. Abrahams will present his findings at a public meeting on Monday in the Howes House in West Tisbury at 4 p.m.

A 19-page executive summary of the report recognizes some minor inequities in the regional district and offers ways to make the formula more fair. But none of the recommended changes would have a significant effect on any one town's contribution, according to the report.

The study was commissioned in the midst of a long-running debate about the cost sharing formula in the small regional district, which includes West Tisbury, Chilmark and Aquinnah. The West Tisbury finance committee has long maintained that its taxpayers carry an unfair share of the financial burden.

West Tisbury selectman John Early proposed the study on annual town meeting floor in April 2004 as a compromise to a finance committee article that asked for the town to withdraw from the district. The other two up-Island towns soon signed on, and the so-called regional school district task force, charged with shepherding the study through to completion, held its first meeting in late August 2004.

"It was a lot more work than anybody really envisioned at the time, but I think Mark's done a great job," said Chilmark resident Janet Weidner, co-chairman of the district task force. "His report is very thorough and I think he answered all the questions posed by John Early's resolution. I'm looking forward to the meeting on Monday."

Town officials first thought the report would be completed in time for the 2005 annual town meeting circuit, but the process grew protracted and encountered a number of bumps along the way. The task force at one point struggled to find a consultant willing to take the job.

Chilmark and West Tisbury selectmen also knocked heads over whether the study should calculate the financial impacts of closing the Chilmark School and operating the regional district out of a single West Tisbury site. Eventually the Chilmark School scenario was removed from the scope of the report - but the West Tisbury finance committee said the report would be incomplete without those numbers, and has since received approval from town voters to commission that analysis as a separate study.

Finance committee members have also questioned the objectivity of the report released this week, noting that it projected enrollment numbers based on the recommendations of school officials.

The report estimated that West Tisbury School enrollment will decline from roughly 300 students this year to 264 in the 2009-2010 school year, while Chilmark School enrollment will increase from 52 to 56 students.

The report also found that different scenarios regarding the future of the up-Island district would result in overall cost increases because the schools would lose state transportation funding currently earmarked for regional districts. It is particularly noteworthy that the West Tisbury assessment would rise in each scenario. The findings include:

* If the regional district dissolves and Aquinnah students attend the Chilmark School for elementary school, the town of Chilmark would save roughly $180,000 while Aquinnah and West Tisbury would pay an additional $80,000 and $570,000.

* If West Tisbury withdraws from the district, but Aquinnah and Chilmark stay together, the town of Aquinnah would see a $40,000 increase, West Tisbury a $500,000 increase, and Chilmark a $200,000 reduction.

* If Chilmark withdraws, but West Tisbury and Aquinnah reconstitute a new district, Aquinnah would pay $14,000 less, while Chilmark and West Tisbury would pay an additional $230,000 and $20,000.

While the executive summary avoids making any political statements, some of the findings suggest that West Tisbury may in fact be paying slightly less than its fair share.

The study suggests that the three towns should update the funding formula to incorporate the school choice program and the Martha's Vineyard Public Charter School, neither of which existed when the Up-Island Regional School District agreement was signed in 1993. Because they are not addressed in the current formula, the regional district distributes costs and revenues from school choice and the charter school to each of the three up-Island towns based on overall enrollment. Mr. Abrahams recommended that the formula should track the hometowns of each individual school choice and charter school student and distribute the corresponding financial impacts accordingly.

Neither change would result in a major effect, but the resulting formula would be more equitable, the report said. The impacts to each town would fluctuate year to year, but the study calculated that if both changes were previously enacted, Aquinnah in fiscal year 2004 would have saved roughly $30,000, Chilmark would have paid $5,000 more, and West Tisbury would have owed an additional $35,000.

A more significant change addressed in the study is a new state formula used to allocate costs in regional school districts. The formula, which is based more on property values and less on school enrollment, is recommended by the Massachusetts Department of Education. About half of the regional school districts in the commonwealth use the new formula.

The Abrahams report calculated that if the up-Island district used the recommended formula in fiscal year 2004, Aquinnah and Chilmark would have paid $160,000 and $110,000 less, respectively, while West Tisbury would have owed an additional $270,000.

The report did not recommend that the up-Island district adopt the new formula, but suggested the towns discuss its implications further.

The report also calculated per-pupil expenditures from both the Chilmark and West Tisbury schools. Prior to the Abrahams study, per-pupil numbers were only available for the regional district as a whole.

While fiscal years 2003 and 2004 per-pupil numbers were released by Mr. Abrahams in a preliminary report last June, the final report this week included fiscal year 2005 data as well.

The new numbers show that per-pupil costs have increased rapidly at the West Tisbury School over the last three years - going from $13,700 in 2003 to $17,300 in 2005. Meanwhile, per-pupil costs at the Chilmark School returned last year to the 2003 numbers of roughly $18,700 after a sharp increase in 2004.

Costs at both up-Island schools are substantially higher than at other Vineyard schools, and among the highest in the state.