A piano instructor examined student progress. He noticed that when students spend less time playing video games, their memorization ability tends to increase. What can he conclude?
There is no correlation between amount of time spent playing video games and memorization ability.
There is a correlation between amount of time spent playing video games and memorization ability. There may or may not be causation. Further studies would have to be done to determine this.
There is a correlation between amount of time spent playing video games and memorization ability. There is probably also causation. This is because there is an increase in memorization ability with a decrease in the amount of time spent playing video games.