A surgeon observes that many of his patients coming in for brain surgery played organized football before the age of 8. The surgeon plans to collect more extensive data on participation in organized football and its potential correlation with brain surgery. What is the purpose of the surgeon's plan?
1) To determine if playing organized football before the age of 8 increases the risk of needing brain surgery
2) To determine if playing organized football before the age of 8 decreases the risk of needing brain surgery
3) To determine if there is a correlation between playing organized football before the age of 8 and needing brain surgery
4) To determine if there is no correlation between playing organized football before the age of 8 and needing brain surgery