Why is it more useful to research the who, what, when of buying rather than the why?

1) Why is it more useful to research the ˜who, what, when of buying rather than the why?
2) You have recently been appointed as the Marketing Assistant for Nescafe, a large coffee manufacturer. The Marketing Director (your boss) has asked you to look over a data set for instant coffee purchases and provide a series of calculations (for the brand performance measures provided below). However, some members of your marketing team are not familiar with the following measures. Briefly explain each of the measures. Why is it important to have an understanding of these in marketing?
a. Penetration
b. Average Purchase Frequency
c. Share of Category Requirements
d. Category Buying Rate
e. First Brand Loyalty
f. Sole Loyalty
How are each of these measures calculated? Provide a formula.