Sam Dillon of the New York Times employs the usual "last-minute dash to employ teachers before the school year begins" story to discuss the real problem.

The retirement of thousands of baby boomer teachers coupled with the departure of younger teachers frustrated by the stress of working in low-performing schools is fueling a crisis in teacher turnover that is costing school districts substantial amounts of money as they scramble to fill their ranks for the fall term. Superintendents and recruiters across the nation say the challenge of putting a qualified teacher in every classroom is heightened in subjects like math and science and is a particular struggle in high-poverty schools, where the turnover is highest.... To staff its neediest schools before classes start on Aug. 28, recruiters (From Guilford County, NC) have been... offering one of the nation’s largest recruitment bonuses, $10,000 to instructors who sign up to teach Algebra I....

< style="font-family: arial,helvetica,sans-serif;"> “The problem is not mainly with retirement,” said Thomas G. Carroll, the president of the National Commission on Teaching and America’s Future. “Our teacher preparation system can accommodate the retirement rate. The problem is that our schools are like a bucket with holes in the bottom, and we keep pouring in teachers.”.... The commission has calculated that these days nearly a third of all new teachers leave the profession after just three years, and that after five years almost half are gone....

So many teacher training, mentoring, support and professional development programs, so little data on the impact they have on retention and, ultimately, student performance.

If you have the research, it is time to take it out and start calculating: 1) how much time and money you can save a school system by reducing turnover, and 2) how much value your teachers add to student performance - itself a money-saving measure represented by costs avoided when students don't need other forms of support, like SES.