Amazon Prime has reached a staggering 80 million U.S. members, according to new findings from Consumer Intelligence Research Partners (CIRP), a doubling from 2015, while comprising about 60% of all Amazon shoppers. Josh Lowitz and Michael Levin, partners and co-founders in CIRP, talked with Multichannel Merchant about the stickiness of Prime membership, the relative value of Prime vs. non-Prime members and competition from Walmart.com.