NATCHEZ — An error in the calculation of scores by the Mississippi Department of Education skewed the performance results of 10th-grade Natchez students.

MDE announced Tuesday there were errors made in the files released to media outlets ahead of the public release Tuesday.

The errors involved results from the Subject Area Testing Program, which tests 10th-grade students on four content areas — Algebra I, Biology I, English II and U.S. History.

MDE Director of Communications Patrice Guilfoyle said Tuesday the original data released included data on students who had retaken the test, when it should have only included first-time test takers.

The error was discovered late Monday, and new data was issued Tuesday morning.

The previous data had shown Natchez 10th graders scored lower in all four categories compared to last year’s scores.

But the corrected data told a different story — at least in two of the four categories.

On the U.S. history test, 76 percent of students scored basic or above, which is up 13.9 percentage points from the 2013 scores. Those students also scored 11.5 percentage points higher on the English II test.

Natchez 10th graders still scored lower than last year’s students on the Algebra I and Biology I tests, but not by as much, the new data revealed.

On the Biology I test, 66 percent of students scored basic or above, which is down 15.3 percentage points from the 2013 scores. The students also scored 12.6 percentage points lower on the Algebra I test.

Natchez-Adams School District Superintendent Frederick Hill was unavailable for comment Tuesday.

NASD Board of Trustees President Tim Blalock said Tuesday the mishap from the state department was an unfortunate one, but not something that would necessarily impact the performance or improvements at Natchez schools.

“Our main concern is the children and making sure we’re reacting to the numbers and what those numbers are telling us need to improve or change,” Blalock said. “But the state’s numbers aren’t the only numbers we rely on.

“We’ve got internal numbers, too.”

Students in the district take assessments throughout the year that are intended to mirror the state tests. The results of the tests are what principals and district administrators use to guide the decision making in the classroom.

The scores released by the state Monday for students in grades three through eight in English language arts and mathematics, as well as fifth- and eighth-grade students who took science tests, were correct.

When the corrected 10th-grade data is factored into data from other grades, Natchez students showed improvement in 11 of the 18 categories in which they were tested compared to the year before.

The Mississippi Department of Education will release accountability labels for each school and district ranking them A through F next month.