There is no general formula for measuring the effectiveness of an advertisement. In pretesting we can just define a series of different functions of an ad and check to what extent they are fulfilled. These functions are: 1. The attention effect; 2. the information provided; 3. the association's (attitudes); 4. the memorability. If pretesting shows that an advertisement meets the above criterions, it may be regarded as adequate. Insufficient results in one of the four functions are a warning to the advertiser: he will become aware of a certain weakness of his advertisement and can plan preventive measures.