A car manufacturer is concerned that dealers conceal unhappy

A car manufacturer is concerned that dealers conceal unhappy customers by keeping them out of surveys conducted by the factory. The manufacturer suspects that certain dealers enter incorrect addresses for dissatisfied customers so that they do not receive the satisfaction survey that is mailed by the manufacturer. If a current survey of the 65 customers at a dealership indicates 55% rate its service as exceptionally good, can the manufacturer estimate the proportion of all customers at this dealership who feel that its service is exceptionally good? Can it estimate the proportion at other dealerships?

Solution

Yes, if this sample was randomly drawn, the point estimate of proportion of all customers is 0.55 or 55%

This cannot be used for other dealer ships because the sample was drawn from only this particular dealership.