The state's Department of Public Instruction estimates half of the schools that failed federal standards of the "No Child Left Behind" act will fail again this year.
So Wisconsin is joining 15 other states that have a confidence interval for determining passing percentages.
The interval is similar to a margin of error in polls or surveys.
The director of pupil services for Eau Claire Public schools says the new formula, along with improved education for specific subgroups, helped remove Eau Claire's two public high schools from failing standards.
"The expectations are very difficult to meet," Tony Beardsley. " I think an inordinate number of schools were identified as having problems with those groups because of the difficulty and the severity of the needs of the kids."
Last year, DPI officials say 108 schools were labeled as failing along with thirty school districts.