I think what it is, is bad sampling procedures. For example, in the study, they had to get permission of parents to evaluate the kids and only 36% ( ! ) of those not in pre-k agreed to be evaluated. So, I think this is just biased sampling at work.
Having looked seriously into this study it does appear to be done correctly. I struggle with it is Pre-K's fault and not what are we doing wrong with K-3, which is were I think our Public Education System (Especially in Urban Schools) are at our weakest. The "common sense" of start early for reading became all 5 year olds must learn to read became my daughters 3 hours of reading a day Kindergarten and 2.5 hours of math with no recesses.
The issue is not that it's done incorrectly, the issue is that the limitations of the available sample are such that there will be a bias introduced. Most parents did not respond to request to be evaluated ! that's a very strong indication of a possible bias
It states that the raw values come from the school database with a sample size of around 3,000 children. Also the teachers were giving the responses at the end of the school year.
The parents did have to sign a letter at some point to be apart of this but it appears that there is an issue with the outcomes. I fully believe what is happening in my Head Start really is making a difference, but it seems to be harder to see the advantages right now with this research paper.
