"The path to real reform begins with the truth," stated Education Secretary Arne Duncan in 2009 during an education forum with the Data Quality Campaign. Sec. Duncan, who argues that policymakers should use "data to drive reform," strongly believes that education policy should be "framed by evidence."

We agree.

So why is the secretary reacting so negatively to evidence about teacher compensation? Writing in the Huffington Post on Wednesday, Sec. Duncan shifted from data to emotion, stating that our report on the compensation of public school teachers "insults teachers and demeans the profession."

He is referring to a section of our report showing that traditional skill measures, such as years spent in school or level of degree obtained, do not provide an accurate salary comparison of teachers to non-teachers. Although public school teachers earn less, on average, than similarly credentialed non-teachers, the wage penalty disappears when teachers and non-teachers are compared using objective measures of cognitive ability, as opposed to years of university education.

Our report is a long and detailed analysis of salaries, fringe benefits, and job security for current public school teachers, intended to add to the state of knowledge regarding teacher pay and education policy in general. It is exactly the kind of research Sec. Duncan should find useful to inform the on-going conversation about reforms that would better reward effective teachers. Our results are clear: Teacher salaries are at roughly market levels, but generous fringe benefits and job security push teacher compensation well ahead of comparable private sector workers.

Sec. Duncan leveled two specific charges. First, he writes that we "exaggerated the value of teacher compensation by comparing the retirement benefits of the small minority of teachers who stay in the classroom for 30 years, rather than comparing the pension benefits for the typical teacher to their peers in other professions."

That is false. While we did use a 30-year veteran teacher as part of a simple example to begin our pension discussion, our actual estimate of pension values is based on the "normal cost" of providing benefits. This is the contribution to the pension fund that actuaries have decided is needed each year in order to have enough money to pay benefits in the future. Actuaries take into account many factors, including the fact that some teachers do not stick around long enough to collect benefits. So our estimate is a true average of what teachers collect. If we actually did what Sec. Duncan suggested we did -- counting only teachers with full 30-year careers -- the pension value would be much higher than what we report.

Sec. Duncan also says that we "appeared to create out of thin air an 8.6 percent 'job security' salary premium for teachers -- despite the fact that hundreds of thousands of education jobs were lost in the recession and teachers continue to face layoffs."

Job security is not the same as a job guarantee. Of course some teachers have lost their jobs, but the data on unemployment show that, over the last decade, public school teachers were only half as likely as workers in other white collar occupations to become unemployed. That extra security has a value, and our paper describes in detail our method for quantifying it.

Aside from Sec. Duncan's sudden aversion to unwelcome data, what is most disappointing here is the lost opportunity to find common ground. We agree with Sec. Duncan that a much more flexible, performance-based teacher compensation system needs to be implemented, to reward effective teachers. Let's also agree to be consistent in pursuing evidence-based reform.

Andrew G. Biggs is a resident scholar at the American Enterprise Institute. Jason Richwine and Lindsey Burke are senior policy analysts at the Heritage Foundation.