How reliable are portfolio tests?

Date of publication: September 1, 1980

Author: Jörg Rehorn


One of the oldest techniques to test the level of attention of advertisements, yet nevertheless still often in practice today, is the portfolio test: the test person goes through a folder usually containing 10 advertisements. Afterwards it is ascertained which products and brands are remembered. A series of tests, respectively re-tests, in 1979 with over 2000 interviews has shown that this method can be unreliable: the same advertisements from test to test can obtain different recall and therefore different awareness values - despite using the same test design, same sample size, same sample structure, same test method, same institute. The paper shows factors which may be responsible for this phenomena and gives recommendations how to improve portfolio test reliability.

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