Question: A researcher would like to evaluate the relationship between a person’s age and his or her preference between two leading brands of cola. In a sample of 12 people, the researcher found that 5 out of 8 people 30 years or older preferred brand A and only 1 out of 4 people younger than 30 years old preferred brand A.

a. Convert the data to a form suitable for computing the phi-coefficient. (Code the two age categories as 0 and 1 for the X variable, and code the preferred brand of soft drink as \(0\) and 1 for the Y variable.)

b. Compute the phi-coefficient for the data.