This study tried to control for all the confounding factors, so it looked at children who were equally intelligent and from the same social-class background, so it seemed as if it was the reading which really helped those children go on and score better on those school tests later in their lives.
Studien försökte kontrollera andra påverkande faktorer, så de tittade på barn med samma intelligens från samma sociala bakgrund, så det verkar som att det var läsningen som verkligen hjälpte dessa barn till att bli duktigare i skolan senare i livet.