I think I&#x27;m not stating my point very well. Apologies for that.<p>The problem with saying that n=80 is that it presumes each &#x27;test&#x27; (student evaluated) was chosen for their treatment independently of each other. This is clearly not true, as entire classes were chosen together. So any variable like &#x27;actually this happens to be the gifted class&#x27; can throw the whole study up or down because that variable was not independent between the students tested.<p>For example, let&#x27;s say we did this same test in America, but two classes happened to be from the wealthiest part of Boston, and two classes were from the poorest part of Detroit. If, as we randomly selected which class was assigned each treatment, we happened to hit the 1 in 4 chance that both wealthy classes were given the &#x27;this is a game&#x27; treatment, would we be ready to say &#x27;the game was the cause of the better test results&#x27;? I don&#x27;t believe so.<p>That is why I find this study flawed, and why I disagree with the idea that n=80. They <i>may</i> be onto something, but they do not have strong statistical evidence supporting their hypothesis.