In the study, the authors were looking at the statistical factors related to teachers leaving their schools. Teacher longevity at schools is correlated with positive educational outcomes, both among standardized test results as well as family satisfaction, student relationship building, and other "softer" measures of educational quality.
So the study, which was focused only on teachers in the Los Angeles school system, which can differ in many ways from most of the school systems in this country, is written in educational-ese and contains lots of data and statistics and such. I glazed over the statistics analysis and chi squares methodology and such that is part of such academic research, and I have a Masters in Education. But I think this graphic, taken from the report, can express one of the most important conclusions:
Annual Teacher Turnover by School Size in LAUSD 2002 - 2007
Click here to see the map in its original size.
The bottom line of this graphic is that I count 30 schools that have a teacher turnover rate of over 40%, and of that number, all but two are charter schools, which means that 93% of such high turnover schools are charters (and I don't know the exact statistics, but I think charter schools are only about 10% of all the schools in LA). So clearly, teachers are much more likely to leave charter schools than traditional public schools.
The question that the study doesn't address, however, is why. Charter teachers tend to be young; is that why more of them leave? (although more leave charter schools than is average for schools in general). Charter schools tend to be newer, which is also associated with higher turnover, but not at the rates seen in this study among the charter schools. Are the young teachers who work at charter schools more naive and/or idealistic than other young teachers, and thus leave when their fantasies encounter real educational situations? Are the demands of charter schools so intense that teachers can only maintain them for a year or two? Do the (sometimes) for-profit charter schools pay their teachers and/or offer fewer benefits or other incentives that make their staff leave for traditional schools? All of these explanations have been offered, but none have been proven.
So I don't know how to explain this data. But I do have a belief (which is backed up by some data) that students are better served by teachers with more experience and/or commitment to the school in which they teach. Therefore, I think the high teacher turnover rates should be at least a yellow caution light for those who seek to expand rapidly the charter school program (such as the Republican legislators, who this year lifted the 100-school cap on charter schools in North Carolina).