In a more familiar discussion of teacher attrition, Richard Ingersoll and Jeffrey M. Kralik have reviewed the literature pertaining to the effect of mentoring programs on teacher retention. Ingersoll and Kralik had to throw out all but ten studies of the 150 studies they looked at for not meeting standard scientific standards a discard rate that seems pretty similar to other efforts by serious researchers who sort through junky ed research. While all ten supported the notion that mentoring seems to reduce teacher attrition, the authors caution that "the findings are seriously limited" for a variety of reasons including "the fact that most of them were not able to control completely for other factors that might also have affected the outcomes noted."