SELECT two Cities of about the same population, in approximately the same climate, and with equally good newspapers.
St. Paul and Minneapolis are fair examples,-but scores of other equivalents can be named or chosen.
Check up carefully the quantity of the Advertised Goods in these two cities which the Retailers have on hand at a given date.
Then ask them to keep record (on a blank form you supply) of the goods in your advertised lines which they stock within the next four months.
Then, run in one of the two competitive cities the "General Publicity" you have already been using.
At the same time run in the other competitive city Reason-Why Salesmanship-on- Paper.
Spend for each kind exactly the same appropriation, and make it sufficiently liberal to show some results on the second month.
Continue this competitive copy for four months, which is the minimum time on which General Advertising can be made to produce a fair measure of Results.
Then, on a certain day, send out enough men to check up the amount of the Advertised goods in the hands of each Retailer at the end of the four months.
Add to the total of goods on hand, at time of starting Test, the goods since stocked in each City.
Then subtract from this total the Advertised goods remaining on the Retailers' Shelves, in each City, at end of the four months' Advertising test.
The difference between will show the quantity of your Advertised goods actually sold to Consumers, in each city, during the four months' period of actual selling test.
The difference between the Value of goods sold in each City during the test period will then be a reliable index to the relative Selling Power of the two Competing kinds of Advertising used.
Now, cross the copy in each City for four months longer.
Use "Reason-Why" in the City where you previously used only current "General Publicity," and vice versa.
Check up the goods on hand at end of the second four months again, as before.
When you find the difference in Sales (with the same expenditure for Advertising) to be again heavily in favor of the Reason-Why copy (as in the first four months), you will have made a Copy Test, that may save you over 25% to 50% of your National appropriation every year afterwards.