1. WASHINGTON Elementary- and middle-school teachers who help raise their students standardized-test scores seem to have a wide-ranging, lasting positive effect on those students lives beyond academics, including lower teenage-pregnancy rates and greater college matriculation and adult earnings, according to a new study that tracked 2.5 million students over 20 years. 2. ...allowing for a deeper look at how much the quality of individual teachers matters over the long term. 3. That test scores help you get more education, and that more education has an earnings effect that makes sense to a lot of people,...differences in teachers mean differences in earnings. 4. ...value-added ratings, which measure the impact individual teachers have on student test scores. It is likely to influence the roiling national debates about the importance of quality teachers and how best to measure that quality. 5. Many school districts, including those in Washington and Houston, have begun to use value-added metrics to influence decisions on hiring, pay and even firing. 6. Detractors, most notably a number of teachers unions, say that isolating the effect of a given teacher is harder than it seems, and might unfairly penalize some instructors. 7. Critics particularly point to the high margin of error with many value-added ratings, noting that they tend to bounce around for a given teacher from year to year and class to class. But looking at an individuals value-added score for three or four classes, the researchers found that some consistently outperformed their peers. 8. The average effect of one teacher on a single student is modest. All else equal, a student with one excellent teacher for one year between fourth and eighth grade would gain $4,600 in lifetime income, compared to a student of similar demographics who has an average teacher. The student with the excellent teacher would also be 0.5 percent more likely to attend college. 9. Replacing a poor teacher with an average one would raise a single classrooms lifetime earnings by about $266,000, the economists estimate. Multiply that by a careers worth of classrooms. 10. If you leave a low value-added teacher in your school for 10 years, rather than replacing him with an average teacher, you are hypothetically talking about $2.5 million in lost income, said Professor Friedman, one of the coauthors." http://www.nytimes.com/2012/01/06/e...achers-to-lasting-gain.html?pagewanted=1&_r=1 And this: "...even if imperfect, well-calculated value-added scores are an important part of evaluating teachers." Ibid. Data informs policy, as it should.