Does chewing gum improve maths grades?

Source: My Paper, 29/4/9, p.A9
Headline: Chewing gum boosts maths scores, says study funded by Wrigley

Quote1:
The study was funded by chewing-gum maker Wrigley. ...

Comment1:
The temptation here is to discount the study because of Wrigley's vested interests in the result. This commits the fallacy Argumentum ad Hominem (circumstantial) -- appeal to one's circumstances -- and must be rejected. We need to look at the merits of the study.

Quote2:
Researchers at Baylor [College of Medicine] studied four maths classes with 108 students aged between 13 and 16 years old ... Half received free sugar-free gum to chew during class and tests, and while doing homework. ... The other half went without.

Comment2:
The half that received the gum is known as the experimental group. The half that did not receive the gum is known as the control group. This model of scientific study is based on the logic of English philosopher John Stuart Mill's Method of Difference. The proposed cause (chewing gum) is applied to one group (the experimental group), and not applied to another group (the control group). Then we watch to see if they show any difference in the alleged effect.

Quote3:
After 14 weeks. the gum chewers had a 3 percent increase in their maths scores on the Texas Assessment of Knowledge and Skills achievement test -- a statistically significant change, said the researchers. ... The gum chewers also got better final grades in their classes.

Comment3:
It turns out that there is a difference. The phrase "statistically significant" means that the difference is greater than could have occurred by chance. We now have initial grounds to say chewing gum improves maths grades. To confirm this, we repeat the experiment.

Quote4:
The researchers found no difference in maths scores between the two groups in another test called the Woodcock Johnson III Tests of Achievement.

Comment4:
The same difference is created between the control and experimental groups, but a different math test is applied. No difference in the alleged effect is found. The initial finding is not replicated. This reduces our confidence in the causal connection.

Comment5:
Note that the study is discounted on its merits, instead of resorting to an ad hominem argument.

END