Shovel More Dirt on Pre-K
Freddie deBoer
So I would ordinarily shy away from doing an old-school blog post that simply links to something else, but this feels like a study that calls out for an exception. I’ve just been reading a paper in the journal Developmental Psychology 1, thanks to a friend’s library access. It’s a pre-K study that has many virtues, including
- Large n (2990 kids)
- Genuine random assignment
- Longitudinal design
- Confirms my priors
… and it says kids who were assigned to the pre-K condition actually did worse than kids who were not.
 VPK = Tennessee Voluntary Pre-K
Pre-K advocates tend to fixate on non-academic indicators as a way to justify pre-K programs. But attendance was mildly worse for the pre-K group:
Attendance rates in sixth grade (proportion of instructional days without a recorded absence) were high for both TN-VPK participants and nonparticipants. Nonetheless, the difference between groups was statistically significant with a slightly higher rate for nonparticipants (97.5% vs. 97.1%, p = .013 for the ITT analysis with observed values). Supplemental Table S11 provides model details for each year (see also Supplemental Figure S3). Sixth grade was the first academic year with a significant attendance difference between conditions, although there were marginally significant effects in kindergarten and first grade.
Nor can we find any solace in disciplinary action:
So, yeah. Looks bad! Random assignment to condition for a large and representative n studied longitudinally shows kids who got pre-K do meaningfully worse than those who didn’t.
“Beware the man of one study!” you might say. But, well, we have many more studies than one showing this outcome, now. I just wrote about it not that long ago: the pre-K research record is most optimistically described as mixed and most realistically described as discouraging. I’ve been writing about it for a long time, actually, and the song remains the same. This chart is out of date at this point, but the overall trend is still informative.
There are always exceptions and there are examples touted as proof that pre-K works. But the drift from the initial positive studies to more pessimistic later studies seems clear, from where I’m sitting, and the most compelling and parsimonious explanation is that we’ve gotten better at doing this research over time, with better study designs and higher data quality. The results are what they are. But liberals are forever looking for magic bullets in education, and a lot of them got very professionally, politically, and emotionally invested in pre-K, and it’s just really hard to get them to confront all the bad news...
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