Do teachers deserve higher wages? Not everyone thinks so.

While most would agree that the people educating America’s children deserve to get paid fairly, how much is enough is a controversial and complicated issue. 

Teachers' wages are declining compared to other workers with similar experience, education, and demographics, according to a report out earlier this month from the Economic Policy Institute (EPI), a Washington-based think tank.

Last year the gap in pay between teachers and other comparable workers was 17 percent, a marked increase from the 4.3 percent difference in wages between teachers and non-teachers in 1996. When including teachers' generous benefits, though, the 2015 pay gap shrinks to 11 percent, according to the liberal-leaning EPI, which calls for higher pay.

“In order to recruit and retain talented teachers, school districts should be paying them more than their peers,” said Lawrence Mishel, president of EPI in an announcement. Along with his co-author of a recent report on the subject, UC Berkeley economist Sylvia Allegretto, Dr. Mishel suggests that unions are important in helping secure better pay for teachers.

“Teachers benefiting from collective bargaining have a wage gap 6 percentage points less than teachers who are nonunion,” report the two researchers.

Low pay is leading to too many teachers leaving the field, too many retirements of experienced teachers, and fewer students interested in the career, say advocates for more compensation for teachers. “A recent study showed that only 5 percent of college-bound students were interested in education,” says EPI.

While most would agree that the people educating America’s children deserve to get paid a lot, how much is enough is a controversial and complicated issue. Some say that paying teachers more would not improve education. The conservative American Enterprise Institute has estimated that teachers already earn more than workers in the private sector with comparable SAT and GRE scores.

“To those who say schools need to pay more for recruiting purposes, we say: The extra money is already there, but teacher quality has not risen to match it,” argued Andrew G. Biggs, a scholar at the American Enterprise Institute, and Jason Richwine, a senior policy analyst at the Heritage Foundation, argued in a 2013 New York Times op-ed.

Drs. Briggs and Richwine wrote that teachers unions interfere with the ability of schools to hire and fire teachers based on their performance.

“Reform of teacher compensation will be most successful in school systems free of the regulatory burdens imposed by union contracts and the education bureaucracy,” they wrote.

Whether teacher pay correlates with student performance is another relationship that’s hard to untangle. Some studies have shown no relationship, while others have concluded that a 10 percent increase in pay would produce a 5 to 10 percent increase in student performance.

According to EPI’s data, states that paid the highest teacher wages between 2011 and 2015 (relative to those of comparable workers in those states) include Wyoming, Rhode Island, Alaska, Montana, and New York.

However, EPI ranked a different group of states highest for 8th grade math test scores in 2013, “adjusted for student characteristics, student family background, school socioeconomic status and race composition, and teacher characteristics.” Those included Massachusetts, Texas, North Carolina, Vermont, and Ohio. North Carolina is one of the lowest paying states, and Texas pays its teachers below the national average.

Ultimately, concluded EPI in a separate study in 2015, the presence of teachers' unions in a state and the levels of spending per student did not influence math test scores. What did contribute to the differences between high-ranking and low-ranking states were rates of childhood poverty and accountability in the education system. Higher childhood poverty statewide and lower accountability meant lower test scores, found EPI.

[Editor's note: An earlier version of this story named Arkansas as one of the states that pays the highest teacher wages. The correct state is Alaska.]