Estimating patients' preferences for medical devices: does the number of profile in choice experiments matter?


Bridges, John and Buttorff, Christine and Groothuis-Oudshoorn, Karin (2011) Estimating patients' preferences for medical devices: does the number of profile in choice experiments matter? [Report]

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Abstract:Background: Most applications of choice-based conjoint analysis in health use choice tasks with only
two profiles, while those in marketing routinely use three or more. This study reports on a randomized
trial comparing paired with triplet profile choice formats focused on measuring patient preference
for hearing aids.
Methods: Respondents with hearing loss were drawn from a nationally representative cohort, completed
identical surveys incorporating a conjoint analysis, but were randomized to choice tasks with two or
three profiles. Baseline differences between the two groups were explored using ANOVA and chi-square
tests. The primary outcomes of differences in estimated preferences were explored using t-tests, likelihood
ratio tests, and analysis of individual-level models estimated with ordinary least squares.
Results: 500 respondents were recruited. 127 had no hearing loss, 28 had profound loss and 22 declined
to participate and were not analyzed. Of the remaining 323 participants, 146 individuals were randomized
to the pairs and 177 to triplets. The only significant difference between the groups was time to complete
the survey (11.5 and 21 minutes respectively). Pairs and triplets produced identical rankings of attribute
importance but homogeneity was rejected (P<0.0001). Pairs led to more variation, and were systematically
biased toward the null because a third (32.2%) of respondents focused on only one attribute. This is
in contrast to respondents in the triplet design who traded across all attributes.
Discussion: The number of profiles in choice tasks affects the results of conjoint analysis studies. Here
triplets are preferred to pairs as they avoid non-trading and allow for more accurate estimation of preferences
Item Type:Report
Additional information:JEL No. C91,I11,I18
Copyright:© The Authors
Faculty of Behavioural, Management and Social sciences (BMS)
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