A researcher conducts a standard multiple regression analysis to predict healthy eating as a function of the following predictors: group identity (sr squared = .10), group norms (sr squared = .25),and age (sr squared = .15). If the total variance accounted for in the dependent measure is 50%, what is the partial correlation squared for group norms?

1. Cannot be calculated without knowing the shared variance.
2. 1.00 (i.e., .25 / .25)
3. .33 (i.e., .25 / .75)
4. .50 (i.e., .25 / .50)