5.3. Ranking (VI)

As an example, the ranking of various phone types was easy for the subjects. The product types were to be placed in a rank order, which was easy for both the elderly and the two expert groups. A Doornbos-Prins test between the groups showed the push-button table telephone to be statistically significantly the most preferred type for the elderly living at home based on each group"s opinions. The expert groups together showed no agreement with the criterion ranking. However, the elderly and the geriatric nurses had quite similar opinions, while the opinions of the elderly and the researchers were less similar.

There was good consensus between the rankings by the elderly concerning the choice of telephone type, and the inter-rater consistency can be considered good. Ranking based on trials with real products, as in paper VI, turned out to be one applicable way of probing the elderly customer’s mind.

The EEE₃ procedure can be described as follows:

1. Experts collect data on the product and its users.

2. End-users rank the product variants supported by realistic communication of concept representations, real prototypes or products.

3. Experts of the end-user groups rank the product concepts.

4. The rankings by the experts and the end-users are compared with a statistical test.

5. (If the experts are known to be valid enough, they can be used instead of an end-user group.)