Jack recommends his new keurig coffee machine to his friend jill. jill buys her own keurig and loves it - studies show that she is now significantly more likely to recommend the keurig coffee machine to another person. what is this effect called?

The effect that could be called to the given scenario above is the referral marketing. The referral marketing is a way of being able to promote products to customers, specifically new, with the use of referrals. It could be seen above as after Jack recommended it to Jill, Jill will now refer the product that she loves to another person that could be a potential new customer.