Those who read the news, either online or in print, would probably have seen this article: “Kids with tuition fare worse”.
In the article, it is claimed that: “In fact, children who received tuition actually scored about 0.256 standard deviations lower on their tests than those who did not (standard deviation is a measure of how spread out test scores are from the average).”
The headline is actually quite misleading, causing people to think that tuition causes worse performance. One needs to read the final part of the article: “The first is that students who receive tuition choose to receive it precisely because they are not doing well in school. In other words, weak performance may be what is driving students to enrol for tuition.”
The correct way to measure the effect of tuition is via a “before and after” experiment. Scores of students before and after enrolling in tuition should be compared to truly see if tuition has any effect. Many tuition centers are already doing this, it is not a rocket science experiment.
Without the “before and after” comparison, the research is meaningless. It is like saying, “People who see a medical doctor frequently have poorer health.”, it is true, but obviously one cannot conclude that medical doctors cause poor health!
Lastly, the research is analysing PISA data (Programme for International Student Assessment). Clearly, there is no tuition centre tutoring PISA, which is significantly different from the ordinary curriculum (I was a PISA grader). As tuition is highly specialized, it is true that tuition can have close to zero effect on PISA scores. It is like PSLE / O Level Math tuition has close to no effect on Math Olympiad scores; even if it is both “Math”, it is possible to score full marks in PSLE / O Level Math but zero marks in Olympiad Math!