More good analysis

has also been analysing the national standards data. he finds:

Decile matters greatly. All else equal, a school one decile higher has about a four percentage point increase in pass rates. But, decile matters at a decreasing rate: moving from Decile 2 to Decile 3 correlates with a 3.3 percentage point increase in maths pass rates while moving from Decile 8 to Decile 9 only improves pass rates by one percentage point.

Class size matters: schools with more students per teacher have higher pass rates. I suspect reverse causation here: for a fixed budget, those schools that are able to run larger classes are likely those that have fewer discipline problems and so are able to put those resources to other uses.

Ethnicity matters. A standard deviation increase in the proportion of Maori students reduces aggregate pass rates by 1.3 percentage points in reading and 2.2 percentage points in math. Similar trends exist for Pacific Island student ratios. I’d be pretty cautious in interpreting this one: if you run things decile-by-decile, the effects mostly disappear. The biggest negative effect seems to hold in high decile schools, but by the time you get to Decile 10 schools, the median school has only 5.9% Maori students. Results then may be a bit sensitive to a few outliers on the right hand side. Like Luis, I’ll refrain from doing much more until the official results come out.

Single sex schools seem to do well; boarding schools seem to do poorly.

All interesting data.

There are decile 1 schools providing pass rates twenty percentage points or more above what we’d expect, given their characteristics (that’s the 0.2 number on the y-axis); there is one decile ten school providing pass rates more than twenty percentage points below what we would expect given its characteristics. Differences in school performance simply do not come down only to decile. Decile’s the most important thing. But differences in performance among schools of the same decile by definition have to be about something other than decile. I can’t tell from this data whether it’s differences in stat-juking, differences in unobserved characteristics of entering students, differences in school pedagogy, or something else. But there’s something here that bears explaining. 

And this is the potential value. Identify the schools doing best and worst, and try to emulate them and help them respectively.

Somehow the left think this is a bad thing!

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