After lasting preliminary studies, since January 1962 the Research Institute of the "Schweizerische Gesellschaft fllr Marktforschung" is carrying out a periodical post-testing survey, the GfM-TREND. Thus, till now about 30 ,000 interviews have been done. The four most important Swiss magazines in German are canvased each month: Beobachter, PRO, Sie und Er, Schweizer Illustrierte Zeitung. In the most important cities of German-speaking Switzerland: Zurich, Basle, Berne, Lucerne and St. Gall, 200 women are interviewed for each magazine; the sample of each magazine being quoted according to the stratification of age and social classes of the periodical in question. The interviews take place before the next issue of the magazine has appeared. Only those women are interviewed who prove in a pre-test having read the issue to be tested. The interview will cover only one magazine, even if the interviewee should have read more than one of the four periodicals. The interviews aim to clarify: - How far are the articles of the editorial staff read; - How far are the advertisements noted; - How far are the advertisements identified; - How far are the copy and illustration of the noted advertisement seen; - Which image is the advertisement noted by: 1. degree of interest; 2. credibility of the message; 3. being tasteful. Identification and image were tested in a split-run by two different methods. In the following are shown the differences in the results due to the chosen method.