EXAMPLE 5.22 Building a Customer Base

The Futures Company provides clients with research about maintaining and improving their business. They use a web interface to collect data from random samples of1000 to 2500 potential customers using 30- to 40-minute surveys.¹⁵ Let’s assume that 1650 out of 2500 potential customers in a sample show strong interest in a product. This translates to a sample proportion of 0.66. What is the truth about all potential customers who would have expressed interest in this product if they had been asked? Because the sample was chosen at random, it’s reasonable to think that these 2500 potential customers represent the entire population fairly well. So the Futures Company analysts turn the fact that 66% of the sample find strong interest in a product into an estimate that about 66% of all potential customers feel this way.