A tooth paste may tend to prevent decay. It may also beautify the teeth. Tests will probably show that the latter appeal is many times as strong as the former. The most successful tooth paste advertiser never features tooth troubles in his headlines. Tests have proved them unappealing. Other advertisers in this line center on those troubles. That is often because results are not known and compared.

A soap may tend to cure eczema. It may at the same time improve the complexion. The eczema claim may appeal to one in a hundred while the beauty claims would appeal to nearly all. To even mention the eczema claims might destroy the beauty claim.

A man has a relief for asthma. It has done so much for him that he considers it a great advertising possibility. We have no statistics on this subject. We do not know the percentage of people who suffer from asthma. A canvass might show it to be one in a hundred. If so, he would need to cover a hundred useless readers to reach the one he wants. His cost of results might be twenty times as high as on another article which appeals to one in five. That excessive cost would probably mean disaster. For reasons like these every new advertiser should seek for wise advice. No one with the interests of advertising at heart will advise any dubious venture.

Some claims not popular enough to feature in the main are still popular enough to consider. They influence a certain number of people—say one-fourth of your possible customers. Such a claim may be featured to advantage in a certain percentage of headlines. It should probably be included in every advertisement. But those are not things to guess at. They should be decided by actual knowledge, usually by traced returns.

This chapter, like every chapter, points out a very important reason for knowing your results. Scientific advertising is impossible without that. So is safe advertising. So is maximum profit.

Groping in the dark in this field has probably cost enough money to pay the national debt. That is what has filled the advertising graveyards. That is what has discouraged thousands who could profit in this field. And the dawn of knowledge is what is bringing a new day in the advertising world.