John Merrow, the respected education correspondent for PBS NewsHour, proposed in a  tongue-in-cheek blog item last week that leading educators and policymakers should sit down to a parlor game called “Multiple Measures.” As he sees it, that’s what it will take for Congress to renew the federal law governing K-12 schools (otherwise known as No Child Left Behind or the Elementary and Secondary Education Act).

Merrow notes that most advocates, Republican and Democrat, want a version of the law that relies on more than standardized test scores to assess school progress. But what should the other metrics be?

We’d like to nominate our favorite measure: chronic absence.

Schools have long used attendance as an accountability metric, but their reporting is typically limited to how many students show up every day (known as average daily attendance) or how many are skipping school (a.k.a. truancy.) These measures are fine, but they don’t tell the whole story.

Daily averages can give you a general sense of how a school is doing, But, they don’t tell you who’s missing too much school or give you any clues to why. Likewise, truancy can identify students who are flouting school rules. But it doesn’t capture those who are missing too much class because of illness, family obligations or suspensions. While these absences are often excused, they still add up to academic trouble.

In fact, research shows that missing 10 percent of the school year for any reason is the tipping point for academic difficulty. The problem starts as early as preschool and kindergarten and continues through high school for many students–at least until they drop out.

Chronic absence is a measure of what proportion of the student body is missing a certain percentage or number of days in the school year. Attendance Works uses a 10 percent threshold, while some state and districts use other definitions. The U.S. Education Department’s Office of Civil Rights has just started asking districts to report how many students miss 15 or more days.

The great thing about tracking chronic absence, is that it can both expose the problem and point to solutions. A look at the data can show which grades need the most attention (The transition years of kindergarten, 6th and 9th grades often have the highest rates.) Cut another way, the data can show which neighborhoods are most affected, signaling that transportation troubles or community violence could be to blame. The data can also identify subgroups of students who are more likely to miss too much school.

Another great thing is that chronic absence can often be turned around when schools and community partners work together to build a culture of regular attendance and use their data to diagnose how to help students and families overcome barriers to getting to school.

In New Britain, Conn., for instance, kindergarten literacy scores rose as the school district cut the kindergarten chronic absence rate by more than half. In Chicago, graduation rates went up when high schools started paying closer attention to attendance and other risk factors in 9th grade.

Tracking chronic absence won’t require school districts to collect any new information. They simply have to analyze their attendance numbers in a different way.

While we aren’t sure what will happen with ESEA re-authorization, we know that the conversation about multiple measures offers an important opportunity to educate policymakers about the best metrics for assessing whether students are on track for academic success.

Join us in calling attention to chronic absence, because we know that if students miss too much school for any reason, none of the other investments in improving instruction will make much difference.