CHOOSE a list of reliable Publications, for a representative month's advertising. Run Current copy in half the number of these publications for that month.
Key each advertisement, in each publication separately, so you will know just which advertisement and which publication each Inquiry results from.
Then, run Reason-Why Salesmanship-in-Type copy in the remaining half of the publications, keying each advertisement separately, in each publication so you will know which advertisement and which medium each Inquiry comes from.
By "keying" is meant that you change the reply address in each advertisement, and in each publication.
Thus, in Munsey's you say "Address 86 State St."; in Woman's World, "75 State St."; and in Wallaces' Farmer you say "6th floor 86 State St."; while in another you say "8th floor 75 State St.," for instance.
By arrangement with the Post Office all replies to these different addresses will be put into your Letter-box, regardless of street address on envelope.
Now, you can tell by the envelope address on each Reply or Inquiry which publication, and which particular piece of copy in that publication, produced it.
Then, when the Inquiries from the competing advertisements cease coming, you can total up the number of Inquiries each publication produced from each particular advertisement.
Now, having the total number of Inquiries from each individual advertisement in each medium, you divide that number into the cost of the Space used for each piece of copy, in each publication.
This will give you the exact cost, per Inquiry, from each separate piece of copy, in each publication.
The cost per Inquiry with your other current Copy may then be intelligently compared with the cost per Inquiry through Reason-Why Salesmanship-on-Paper. Now, cross the copy for the second month's Advertising Test.
By this is meant,-insert your other current Copy, which appeared last month in Munsey's, in this month's Wallaces' Farmer, for instance.
And, the "Reason-Why" copy which appeared last month in Woman's World you now insert in Munsey's of this month.
This gives a fair distribution of Mediums to each competing Advertisement. When the Inquiries cease coming from this second month's insertion, make the same record as before of Cost per Inquiry, for each piece of competing copy from each publication .