Some books explain everything, like the Bible, The Bill James Baseball Abstract and (a personal favorite) Charlie Brown’s Super Book of Questions and Answers. They may be difficult to wade through, but well worth the time.

Add to that list the most complete examination of the dropout issue I have ever seen, Russell W. Rumberger’s “Dropping Out: Why Students Drop Out of High School and What Can Be Done About It,” just out from Harvard University Press.

Rumberger, a professor of education at the University of California at Santa Barbara, and educational partnerships vice provost for the UC system, examines every complex nuance, summarizes every important research paper and demolishes every Internet myth. His book is a masterpiece, something education wonks will keep close by.

Its only drawback, for which you can’t blame Rumberger, is that it is profoundly depressing. I have believed for some time that dropouts, the 30 percent of students who leave high school before graduation, are the least soluble problem in U.S. education. Rumberger has evidenced-based answers on how to approach the issue. But he is too honest and too meticulous to hide the fact that progress will be difficult.

The reasons for that are complex — a mix of poverty, culture, politics, administrative priorities and other factors. Among his more disheartening conclusions is that schools can’t reduce dropouts unless they have enough money and personnel and — most troublesome — stick with proven approaches. Many school leaders, as teachers know, have the attention span of my 2-year-old grandson. Just because a program has a good track record and a competent staff is no guarantee that it will continue to be supported, particularly in bad budget years.

Rumberger still has hope. He identifies which programs have had the most success keeping kids in school, while noting where their progress was uneven. He suggests five fundamental changes in public education necessary for significant improvements in graduation rates:

1. Redefine high school success. The measure of a school should not be just mastery of reading, writing and math, but what are called noncognitive skills, such as motivation, perseverance, risk aversion, self-esteem and self-control. This would help both potential dropouts and kids going to college who need work on their social skills.

2.Change the dropout accounting system so schools aren’t rewarded for transferring problem kids. Even students who spend only a semester in the ninth grade before transferring to another school should be counted when the original school calculates how many ninth-graders completed high school four years later. Otherwise, schools will have an incentive to send students most likely to drop out to other schools rather than try to help them.

3. Stop trying to improve schools by forcing them to change their practices over the short term. Instead, help them build their capacity to improve, with more money and staff, over the long term.

4. Work harder to desegregate schools. Rumberger cites a study that found two-thirds of high schools with more than 90 percent minority enrollment had fewer than 60 percent of their students remain in school from ninth to 12th grade. “In short,” he writes, “it matters with whom one goes to school.”

5. Strengthen families and communities. Compared with other developed countries, the United States has one of the highest rates of children living in poverty. Those are the kids most susceptible to dropping out. Anything that improves the health and job security of school neighborhoods improves graduation rates. More early children education and preschool are also useful.

These ideas vary in practicality. Number 2 has the virtue of being the least expensive. Number 4 is the least likely, given the absence of elected officials who want to repeat the desegregation battles of the 1970s.

We can’t make any improvements, however, without knowing what hasn’t helped dropouts, and why. On those vital questions, this book will be the best resource for years to come.