Armed with these figures, the Return On Investment Calculator determines how many sales and how many prospects the campaign must deliver in order to be a success.
In one example, to generate a 20% return on his ad investment, the campaign needed to attract only 29 customers! Our fictitious station had a cumulative audience of 100,200 listeners per week. This means only 0.028692 percent of the audience needs to respond to his message (less than 3/100th of a percent) or 1 out of each 3,455 listeners!
Your closing question: "When 100-thousand people hear your ad message, do you feel at least 29 of them will find it compelling enough to come shop your store?" If the client says "no" to that question, he understands the problem is his offer -- not the medium he is using.