Mississippi’s improving high school graduation rate is one piece of good news in a state where the education picture has often been dismal.

But new numbers could indicate those improvements are not as substantial as they seem.

The key question revolves around changes that the state approved in 2014 to graduation requirements. Before then, every student had to pass standardized subject area tests in algebra I, English II, biology I and U.S. history. The idea was to make sure students were learning the basics no matter where they attend school.

“You do want to know when that student gets that diploma, that the student learned something,” said Nancy Loome, executive director of the Parents Campaign. The lobbying group has historically supported graduation exams. The subject area tests began in 2003, replacing an older exit exam called the Functional Literacy Exam, which had been given since the 1980s.

But many students didn’t graduate because of the tests, and superintendents pressured legislators to ditch them. To block lawmakers from killing the tests entirely, the state Board of Education voted in 2014 to allow students to graduate if they could show alternate measures of proficiency. They include scores of 17 better on parts of the ACT college test, grades of C or better in a college course the student took while in high school, or certain scores on military entrance or career technical exams, combined with a career certification.

Right now, students can also pass if they fail a subject-area test but had high class grades, or get high enough scores on the other three tests. Beginning next year, the subject area test will count for 25 percent of the student’s grade in the applicable course it covered. That means students whose regular grades are average or better can bomb the test and still pass the course.

At the same time those changes were made, Mississippi’s graduation began improving, rising from 74.5 percent of students in the Class of 2014 earning a diploma over four years to 82.3 percent of students whose four years of high school in spring 2016. That latter level is close to national averages.

In the 2016-2017 school year, about 5,400 students — close to 20 percent — earned diplomas based on the alternate options, while about 23,000 passed all four subject-area tests. Charlie Smith, editor of the Columbian-Progress newspaper in Columbia, first uncovered these numbers.

Department officials warn that the data might be incomplete, but it seems clear that a substantial fraction of students are graduating using those other pathways. If they still were required to pass the tests, some more likely would, because districts previously pushed hard to get students to retake any exams they had failed, sometimes multiple times.

Mississippi is far from alone in demoting the importance of graduation tests. But are those 20 percent not passing Mississippi’s tests adequately prepared? It’s hard to tell.

Smith is unimpressed with Mississippi’s policy, saying it’s allowing “educators to slip students through who don’t really know enough.”

“All it does is hide the truth to make the education bureaucracy look better,” he wrote last week.

Education officials dispute that take. Mississippi Department of Education Chief Academic Officer Kim Benton says state officials can’t say how much of the graduation rate change stems from the options. But she says the options are meant to be equal in rigor to the tests.

“In no way are we lowering standards,” Benton said.

She says levels of achievement are improving by other measures, making her confident that Mississippi isn’t graduating unprepared students.

“You see the trends moving in a positive manner, which is what you want to see,” Benton said.

Jeff Amy has covered politics and government for The Associated Press in Mississippi since 2011. Follow him at http://twitter.com/jeffamy. Read his work at https://www.apnews.com/search/Jeff_Amy.