concluded with a paragraph like this:
In four countries—Australia, Hong
Kong, Scotland, and the United States
—our identification strategy leads to
extremely imprecise estimates that do
not allow for any confident assertion
about class-size effects. In two
countries—Greece and Iceland—
there seem to be nontrivial beneficial
effects of reduced class sizes. France
is the only country where there seem
to be noteworthy differences between
mathematics and science teaching:
While there is a statistically
significant and sizable class-size
effect in mathematics, a class-size