Maryland's scores on a national reading test may have been inflated because the state's schools excluded a higher percentage of special-education students than any other state, according to data from the U.S. Department of Education.

The National Center for Education Statistics, which administers the test, estimates that Maryland's scores were 7 points higher for fourth-grade reading and 5 points higher for eighth-grade reading because of the exclusion.

Maryland has always earned high scores on the National Assessment of Educational Progress, and its steady increases in test scores over the years has helped earn it the ranking of No. 1 in the nation by Education Week, an often-quoted measure.

"When exclusion rates are higher, average scores tend to be higher than if more children were tested," said Larry Feinberg, assistant director for reporting and analysis for the National Assessment Governing Board, an independent body that sets policy for NAEP.

Maryland excluded 66 percent of fourth-graders with disabilities for the reading test, far higher than the national rate of 16 percent. The state with the second-highest rate of exclusion of special-education students was Georgia, with 32 percent.

In eighth-grade reading, the rate was 60 percent, again the highest in the nation and far above the national average of 15 percent.

The state's exclusion rates for math are not as high.

Which students are excluded from the test are decided at the school level, according to state officials. In Maryland, some students with disabilities are given special accommodations during their state tests that allow a person to read them the questions. The student then supplies the answers.

This so-called "read aloud" accommodation is not allowed on the NAEP, so many schools decided to not give the NAEP to those students, said Clayton Best, the state's NAEP coordinator.

Best said schools take seriously the accommodation because each student has a written legal agreement that outlines what services and accommodations he or she will get.

Maryland's exclusion rate is much higher, Best said, because other states don't allow any questions to be read aloud on their state tests.

Best said that Maryland is "absolutely not" gaming the test. He said there is no benefit for a school to hold back testing a student because individual student and school scores on NAEP are never reported to the public.

Jason Botel, executive director of the policy, research and advocacy nonprofit MarylandCAN, said the state should reduce its exclusion rates.

"Our children with disabilities are just as capable of achieving as other states' children with disabilities; we should be committed to getting an honest assessment of their learning. We can't claim to be #1 while excluding so many children from the NAEP," he said in an email.

Other NAEP data show that other Maryland scores may have been inflated by the high exclusion rates. For instance, Maryland has the highest state scores for students with disabilities, but the lowest proportion tested.

Officials overseeing the NAEP have been putting pressure on states to reduce their exclusion rates for some time and recently set a goal of having 95 percent of all students in each state's sample take the test. Because of the exclusions, Maryland was the only state in the nation that did not meet that goal in fourth-grade reading.

NAEP, also known as the Nation's Report Card, has been given to a sample of students in each state for the past two decades. The test is considered one of the most reliable assessments of what progress students are making in reading and math in fourth and eighth grade.

While the National Center for Education Statistics does not release the exact number of students given the reading test, Best said it was between 3,600 and 4,200 students, a very small percentage of the tens of thousands of public school students in the state who are taking the Maryland School Assessments.

Overall, 44 percent of fourth-graders and 43 percent of eighth-graders in Maryland achieved proficiency in reading, compared to 34 percent and 35 percent, respectively, in the nation.

Exclusion rates in Maryland on the math test went down significantly in fourth grade this year, when the national testing officials began allowing some students with disabilities to use a calculator. Maryland, which has allowed special education students to use calculators on state tests for some time, previously had been excluding special-education students because of that rule.

This year, when Maryland was in line with the rest of the nation, Best said, its scores dropped 2 points, noting that the exclusion of special education students most likely had helped Maryland post higher scores in 2011.

liz.bowie@baltsun.com