Chronic absenteeism, largely regarded as a problem for school districts serving poor students, is actually much more widespread.

Rich or poor, urban or rural, large or small, 89 percent of all school districts struggle with some level of chronic absenteeism, according to a report released Tuesday by Attendance Works, a national advocacy organization.

Still, half of all chronically absent students were concentrated in only 4 percent of the country’s school districts, including New York City.

Using federal data to pinpoint how many students missed 15 days or more of class, the report found that 3.5 percent of students in New York City were chronically absent in 2013-14 — a surprisingly low number that the city’s Department of Education acknowledged was an error. In fact, 31 percent of students were chronically absent, according to the city’s own analysis using the federal definition.

To calculate chronic absenteeism, the city usually uses the more broadly accepted standard of students who have missed 10 percent or more of the school year — typically 18 to 20 days. Under that standard, the rate in New York City was:

  • 27.6 percent in 2013-14
  • 25.5 percent in 2014-15
  • 25 percent in 2015-16

Kim Nauer, education research director at the Center for New York City Affairs, said accurate data collection is crucial for figuring out who misses school, and why.

“If you track chronic absences and then you look at the schools that have really high rates … that allows you to deploy your resources to those schools,” she said.

The picture was further muddied on Friday when the New York Post reported that Chancellor Carmen Fariña had misreported the chronic absenteeism rate for Renewal schools by roughly 20 points at a presentation to state officials in October. A spokesperson for the Department of Education acknowledged the error to the Post, but that mistake is unrelated to the federal undercount.

Hedy N. Chang, executive director of Attendance Works, said she was confident the federal data accurately reflects large-scale trends and offered an explanation for why some of the numbers may be off.

“The conclusions nationwide are really sound,” she said. “This was self-reported data and it was a first-time data collection.”

New York City has been considered a leader when it comes to both tracking and addressing chronic absenteeism. Real-time data systems allow schools to flag individual students who miss school often, and the city has pioneered mentoring programs that have been replicated across the country.

An evaluation of programs started under former Mayor Michael Bloomberg found that students were 52 percent more likely to stay enrolled in high school, and poor, minority students were 15 percent less likely to be chronically absent.

Mayor Bill de Blasio has also taken on the issue, partly through the launch of dozens of “community schools.” Those schools receive extra funding for everything from mental health supports to additional staffers tasked with keeping an eye on attendance.

Research has shown that students who are chronically absent are more likely to fail classes, be suspended and drop of out of high school.

“We know that chronic absence is a huge, overlooked factor dragging down student achievement,” Chang said. “We need to figure out how to bring everyone together to get kids to school.”