Welcome to Econ Talk, part of the Library of Economics and Liberty. I'm your host Russ Roberts

of George Mason University and Stanford University's Hoover Institution. Our website is econtalk.org

where you can subscribe, find other episodes, comment on this podcast, and find links to

another information related to today's conversation. Our email address is mailadicontalk.org. We'd

love to hear from you. Today is August 5th and my guest is Eric Hanna-Shek, the Paul and

Jean Hanna senior fellow at Stanford University's Hoover Institution. Rick, welcome back to Econ Talk.

Thanks for having me again. Our topic for today is teachers and education. We're going to

base our conversation around a very provocative paper you recently published and we'll put a link

up to that on the site. What we're going to talk about is the importance of the teacher and the

educational process and how we can measure it. Obviously, good teachers are better than bad ones,

but we want to start with this general question. What is the relationship between teacher quality and

student achievement? The one thing that we've found from decades of work now on what determines

achievement of students is that the most important aspect of schools is the teacher. There's been a

lot of work done, some of it controversial, because what the work finds is that it's not the

commonly measured attributes that we call quality, like having a master's degree or having more

experience, but in fact, some people are better at it than others and some people are worse at it

than others, and that's what I would call the value of teachers or the importance of teachers.

And what are some of the magnitudes? We have some idea of the magnitude of what a good teacher

will do relative to a bad one. Well, some work that I did a while in the past in a inner-city

school in Gary, Indiana, where there were all poor kids, we found that some teachers got a year

and a half of learning in an academic year, other teachers got half of a year of learning.

So if you think about that, it says that in one academic year, students can come out a year

...