Understanding how National got into such a mess over class sizes after Budget 2012  - trade-offs, downsides and backdowns.

John Hattie's book Visible Learnings brings together over 800 meta-analyses to rank 138 influences on educational achievement. Five make the students worse off. Some have very little effect. For instance class size is 0.2 –  Hattie is dismissive of anything below 0.4 on his measure – but its effect is still positive. There are 105 other influences ranked above it.

The ranking method involves measuring the share of the total variation of achievement which can be explained by the particular influence. Hattie suggests that  the effects of reducing class size may be small, because teachers do not adapt their teaching styles to different circumstances. He keeps coming back to the style and quality of teaching as key points for improving educational achievement. The implication is that by putting more effort into the teachers we can get a bigger return from smaller class size. Even so the research evidence supports the public intuition that smaller classes are better, even if the teachers do not change.

An economist has a doubt about the usefulness of the Hattie measure for public policy purposes. It is not that it is wrong, but that it ignores costs. Reducing class size is probably one of the most expensive changes among the 138 influences. It would be good to have the Hattie list ranked by cost-effectiveness; it is likely that class size would be ranked much lower, perhaps near the bottom, just above the five duds. Because it is so expensive, the cost effectiveness of reducing class size is near enough to zero. Some of the influences that Hattie ranks below class size are almost costless to implement. Better to do them; yet it's better again to do those which are higher and are near costless too.

So how did we get into the muddle in which the government said that, quite contrary to the evidence, there are no gains to be made from reducing class size and no losses from increasing it? What happened is indicative of a wider problem the government is facing.

The 2012 budget had a tight expenditure restriction as a part of the government strategy of eliminating the internal deficit without increasing taxation. What ministries were allowed to do, though, was reallocate within their capped expenditure.

Suppose a ministry had a new very cost-effective programme but there were no extra funds to implement it. It could obtain the funds by reducing spending on a low cost-effective program. That is what the government was trying to do in its education budget. In order to spend more on teacher training, it proposed reducing class sizes to fund it.

That seems to an economist to be a sensible trade-off to contemplate. But to be honest, the trade-off has to admit that educational achievement would be reduced from larger classes, although it is likely to be more than offset by gains from better teacher training. The public might not like the  cuts, but it would be clear to them what was happening.

However all governments in general – and the current one in particular – are unwilling to admit that their actions may have downside effects even if the overall impact is positive. So in this case it had to deny that class size mattered – contrary to common sense and to the research evidence. There was a plethora of releases before the budget announcing new programs with benefits, but nary a mention that they would be funded by closing other programs. As a rule the bad news will trickle out and the public will be grumpy, long after the benefits of the new programs are thought to be normal.

I really don't know how much the government is aware of what it is doing. Very often deceiving the public – such as there are no downside effects even when they are substantial – ends up with the politicians deceiving themselves. That is what happened with the proposed reductions in class size. The government was totally unprepared for the uproar which followed, and had so forgotten what it was doing that it was unable to cope with the public agitation; hence the backdown.


Footnote: Immediately below class size in Hattie’s ranking is charter schools. It might seem then that, providing the initiative has a very low cost, they should be proceeded with. I am, however, reluctant  to come to that conclusion. The research is from the United States which has a very different educational structure from New Zealand, and its findings may not transfer here. Indeed I thought long and hard before I concluded the overseas evidence about class size probably applied to New Zealand. Even so, if Hattie is right and the key is how teachers adapt, it is possible that ours adapt better than those in the jurisdictions where the research was done and the cost effectiveness of reducing class size is lower here.

Comments (5)

by Terry Crooks on July 05, 2012
Terry Crooks

Thanks, Brian, for an interesting post. One issue is worth considering.  The studies that John Hattie used to assess the infuence (effect sizes) associated with varying class sizes compared performances on particular measures of student outcomes.  Most commonly, these were measures of achievement in a small range of subjects, very often focussing heavily on factual learning and simple comprehension. Such learning is likely to be least dependent on class size.  

It is reasonable to predict that there would be stronger benefits from smaller classes if the variables being measured were such things as the development of thinking skills, ability to anayse, evaluate and synthesize information, or development of positive attitudes and contributions to the community life of schools. Such things are likely to depend more on the extent of personal interaction with teachers and resulting opportunities to discuss and debate with them, and receive direct feedback.  These opportunities clearly are inhibited by larger class sizes, and so larger effect sizes could be anticipated from studies with such outcome variables.

by Philip Grimmett on July 05, 2012
Philip Grimmett
Through all this discussion little has been made of Treasury's Gabriel Macklouf's analysis of student performance in education which he delivered via various media prior to the budget, but which underpinned the government's rationale for the debacle of justifying higher student numbers in the classroom. "... If we lift students performance to match the top performing OECD countries, we could raise G. D. P. by 3 - 15% by 2070." (!!!) Yikes. Is this fellow for real? 2070 ! Is this credible? Is he credible? To quote Tim, "Am I missing something here?" I await your responses with interest.
by onsos on July 05, 2012

Meta-analysis is useful, but is fraught with problems. The terms and measures used are critical to interpreting the results, and the necessary precision has not been brought to bear in media and political discussions of Hattie's work.

As an example: Class sizes are not synonomous with student:staff ratios. I haven't got the time, now, to read Visible Learning and ascertain just how these terms are being defined, but I suspect that the discussion there does not reference student:staff ratios, given that the term conntly cited is "class sizes".

The implications of this conflation are significant.In the NZ public-school context, the latter are determined (largely) by the government, but how staff and students are allocated is determined by schools. What follows are strategies schools are using in the allocation of their staff, which result in larger class sizes to improve teaching, but which do not change staff:student ratios.

More difficult classes (lower stream, or unit standards oriented classes) are often allocated fewer students than classes for already high-achieving students. This is likely to lead to results suggesting that larger classes are more effective, because already achieving students are likely to learn more than students who are struggling.

Larger classes are used to reduce the amount of time teachers spend in the classroom. That is, each teacher would have the same teaching load, concentrated into fewer classes. This would allow teachers to plan and prepare their classes more effectively, leading to better teaching, while increasing class size.

In primary schools, staff are often allocated to remedial teaching, increasing class sizes.

Team teaching can lead to large classes, with no change in teacher:student ratios.

Specialist teaching staff may be used, freeing classroom teachers for planning and prep work.


by danniel on January 31, 2013

I wish I could say that this is the only problem in our educational system but unfortunately there's a lot more than that. Starting from class size, funding, modernization projects and ending with college online options, they are all matters that need to be discussed. So many things are changing in such a short while, in these days we really have be ready for anything.

by rickk on April 23, 2014

Low budgets in education lead to bigger class sizes. The truth is that we don't need researchers to tell us that bigger classes can yield weaker results in student education. We shouldn't compromise when it comes to education. I read some revealing facts about this on Edlantis.com. We should all be aware of these facts.

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