Poor school attendance resulted in lower test scores for Hawaii fourth- and eighth-graders who missed more days than their peers, according to a national study released Tuesday linking school attendance to student achievement and learning.

Isle public school students who reported missing three days or more of school in a month scored significantly lower in reading and math on the 2013 National Assessment for Educational Progress than those who reported no absences in the month before the test.

Hawaii’s scoring differences, among the highest in the nation, suggest students with more absences have math and reading skill levels that lag one to two years behind their better-attending peers, according to the report by Attendance Works, a national initiative dedicated to reducing chronic absences in U.S. schools.

"The goal of this report is to show that it makes a difference if you attend school. It’s clear if kids are missing too many days, they are scoring lower on the NAEP, a marker for student achievement," said Phyllis Jordan, spokeswoman for Attendance Works and a co-author of the study.

Nationally, as many as 7.5 million students miss a month of school each year, or three days on average a month over the 10-month school year, the report said. Chronic absences as early as preschool can predict poor attendance and performance in later grades, and by sixth grade is a leading indicator that a student will drop out of high school, the organization says.

One possible explanation for Hawaii’s pronounced scoring differences could be the state’s efforts to increase rigor in the classroom through adoption of the Common Core standards and to raise the quality of teaching by implementing a new performance-based evaluation system.

"It could be a reflection of high-quality instruction that makes it hard for kids to make up when they miss days," Hedy Chang, director of Attendance Works and a co-author of the study, said in an interview. "We don’t know for sure, but based on other studies, sometimes the more rigorous the instruction, the more each day of absence matters because it’s hard for parents to replicate and for kids to make up."

Hawaii education officials agree and are quick to point out strides the state’s public schools have made over the past year since turning attention to reducing chronic absenteeism as part of a host of educational reforms.

The state as a whole reduced its chronic absenteeism rate — reflecting students who are absent 15 days or more — among elementary schools last school year to 11 percent of students from 18 percent the year before, meaning 5,500 fewer students overall were chronically absent.

Mililani Ike and Hokulani elementary schools boast the lowest rates, at 2 percent, while Nanaikapono Elementary in Nanakuli has the highest rate, at 32 percent.

"Schools have really done a lot to make the lessons and learning more engaging for our students, more relevant for students, more challenging for students. When kids want to go to school they’ll attend more, and not just attend more, but learn more," said Department of Education Deputy Superintendent Ronn Nozoe. "Changing the learning experience has been a big push from our teachers and principals."

Attendance Works did a state-by-state analysis of testing data from the National Assessment for Educational Progress, which is administered every two years to a sample of fourth- and eighth-graders in the 50 states, the District of Columbia and Department of Defense-run schools.

About 6,300 Hawaii fourth-graders and 5,500 eighth-graders took the test last year, and nationwide more than 376,000 fourth-graders and 341,000 eighth-graders took the exam.

In addition to testing math and reading proficiency, the exam asks students nonacademic questions, including how many days of school they missed in the month before the exam, which is given during a testing window from January to March.

"It’s a snapshot in time to give states a sense of where they stand," Jordan said.

Twenty-three percent of fourth-graders and 24 percent of eighth-graders here reported being absent from school three or more days in the month prior to the test. Nationally, the rates were 19 percent and 20 percent, respectively.

Although Hawaii received national praise for overall gains students made on the NAEP that year, including the state’s fourth-graders scoring higher than the national average in math, marking the first time Hawaii has topped the national average in any subject since state results were first recorded in the 1990s, the attendance study found:

» A 19-point difference in Hawaii’s fourth-grade math scores between students who reported three or more absences and those reporting none — the highest point difference in the nation, and higher than the national average of 13 points.

(The report says a 10-point difference is "about equivalent" to a one-year gain or drop between grades four and eight.)

» A 17-point difference in fourth-grade reading scores between those two groups of students. The national average was 11 points.

» A 22-point difference in eighth-grade math scores between the two groups of students. The national average was 18 points.

» A 15-point difference in eighth-grade reading scores between the two groups of students. The national average was 13 points.

The report’s authors noted Hawaii’s efforts since then to curb absences, calling the state a "poster child" for improving attendance rates. Hawaii is one of 17 states that track chronic absenteeism data.

Nozoe said the DOE chose chronic absences as an indicator for school success when developing its Strive HI accountability system for schools. Five percent of an elementary’s school performance rating is now based on its chronic absenteeism rate.

Some schools have led awareness campaigns and sign-waving events to boost attendance, while others are working to improve access to health care in rural areas so students don’t miss school for medical or dental appointments.

"The data in the report confirms that what we’ve been working on (reducing chronic absences) is one of the right things to be working on. Every day, every minute, of school matters," Nozoe said.