Longer schooldays

A recent assertion in the media (and of Gove) is that longer schooldays would lead to better performance and make life easier for working parents (see here, you can even give your opinion here). The latter is probably true but of course, in my opinion, the task for education is not to babysit children. In line with the request for evidence-based research I will present some facts and graphs. As Gove specifically refers to Asian countries I think it is relevant to use international indicators to study the hypothesis that ‘more hours lead to better performance’. Of course, it’s possible to criticize some of these indicators, but it is based on these indicators that international comparisons are made. I made use of:

– Year 8 TIMSS 2011 results for mathematics (source)
– PISA 2009 results (source)
– OECD Education at a glance data from 2012 (source)

I focused on lower secondary education as this seems best aligned with Year 8 TIMSS results.

The first scatterplots I made plotted the average number of hours per year of compulsory instruction time in the curriculum for 12-14 year olds, against the TIMSS 2011 maths result. Later, I also did this against PISA 2009.

There is a very small (not significant) correlation between these variables. We can’t conclude that a larger number of hours is correlated with TIMSS and PISA performance. I then looked at teaching time:

After having seen this blogpost, confirming this, I also looked at teaching days, as a comment on the blogpost seems to suggest that there is a small positive correlation between teaching days per year and performance (note I consistently say ‘correlation’ as causal effects are very difficult to prove).

Indeed, there is a small positive correlation. This, however, can be explained by hypothesizing that some countries have short days and others have long days. To explore this hypothesis I subsequently computed the ratio of the average number of hours per year of compulsory instruction time in the curriculum for 12-14 year olds, and days of instruction for lower secondary education. Plotting these:

This suggests there is small negative correlation between the average number of hours per day against PISA and TIMSS performance. I conclude that there is no basis for the conclusion that more school time increases performance. Actually when looking at a number of OECD indicators (and also including indicators for press freedom, the GINI index for inequality, and the Human Development Index) there only seems to be one very strong correlation for both PISA snd TIMSS (which makes sense as both are strongly correlated): a higher salary per hour of net contact (teaching) time after 15 years of experience. There is a significant positive correlation between these variables.