Fig. 1: “Cards” with stimulus examples as used in a survey on DVD players
With the classic full profile method, complete product examples serve as stimulus material. Ideally, these are real, tangible objects. But normally, descriptions of the different attribute combinations are provided on cards, or visual images are used. All of the examples must be rated or ranked by the respondents in order of preference. This method quickly reaches its practical limits when the study design becomes too complex. Respondents can be expected to cope with between 3 to 5 attributes with 2 to 5 levels each. The number of stimulus examples required can be calculated using the formula "number of levels minus number of attributes plus 1". More than ten to twelve examples should not be used in a normal sample of respondents (in other words, one in which the respondents do not possess a particularly high degree of interest in the subject material).
The stimulus examples are subject to a variety of restrictions, meaning that they can only be created with the help of a computer program.
