Having designed the four prototypes, the project team tested them with thousands of customers using discrete choice analysis, which requires people to make a sequence of explicit choices when presented with a series of product options. The researchers began by amass- ing a detailed list of the attributes for each proto- type—ATM fees, overdraft fees, credit monitoring, customer service hours, and so on. They presented respondents with several sets of checking accounts that varied on these attributes, asking them to select which prototype from each set they preferred. This process was repeated several times, as attributes changed according to an experimental design, until the team derived the winning combination of attributes.