PS_Dahiya, I have a question for you based on your explanation.
You are saying that "
The only thing that can weaken the first study is another reason for increase in aggressive behaviour. "
The first study says that TV has an influence in the agressive behavior, the second study doesn't show another reason for the aggressive behavior, I agree.
What I don't understand is, the second study did not find any change in behavior between 1973 to 1975. Then does it not cast doubt on the first argument?
Lets take another example.
One study says that sudden increase in cases of malaria in city X is presence of standing water in the vicinity of city X due to extreme rainfall this year. Standing water attarcts mosquitoes . Other study say that city Y that have climatic conditions, including rainfall, same as those observed in city X this year, the cases of malaria did not rise this year.
Lets analyze this:
As in any cause effect relationship, ask yourself a questiion: Is the cause given the real cause of the effect? What if the incease in cases is due to some other insect that got favourable conditions due to extreme heat in city X.
But second study says that there is no increase in number of cases in city Y eventhough climatic conditions in both cities are same. If there would have been other cause then cases would have gone up in city Y. This means second study is eliminating the alternate cause for the effect. Hence its supporting the first study.
Hope this helps.
I made this question myself.
SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008