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The European Journal of Health Economics
Published in: The European Journal of Health Economics 4/2012

Open Access 01-08-2012 | Original Paper

The way that you do it? An elaborate test of procedural invariance of TTO, using a choice-based design

Authors: Arthur E. Attema, Werner B.F. Brouwer

Published in: The European Journal of Health Economics | Issue 4/2012

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Abstract

The time tradeoff (TTO) method is often used to derive Quality-Adjusted Life Year health state valuations. An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences. In particular, fixing the duration in the health state to be valued and inferring the duration in full health that renders an individual indifferent, causes valuations to be higher than when the duration in full health is fixed and the duration in the health state to be valued is elicited. This paper presents a new test of procedural invariance for a broad range of time horizons, while using a choice-based design and adjusting for discounting. As one of the known problems with the conventional procedure is the violation of constant proportional tradeoffs (CPTO), we also investigate CPTO for the alternative TTO procedure. Our findings concerning procedural invariance are rather supportive for the TTO procedure. We find no violations of procedural invariance except for the shortest gauge duration. The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.
Appendix
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Footnotes
1
The TTO scores were skewed to the left for all time horizons, rejecting a normal distribution, so we do not report paired t tests.
 
2
This number is comparable to that of Bleichrodt et al. [2].
 
3
The latter finding may be related to the fact that there was less precision possible in eliciting preferences for the longer gauge durations, since the number of iterations was fixed, while the number of years between the subsequent steps was obviously larger. As a result, it was not always possible to return a value of exactly 46, causing many subjects to elicit a value somewhat below 46.
 
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Metadata
Title
The way that you do it? An elaborate test of procedural invariance of TTO, using a choice-based design
Authors
Arthur E. Attema
Werner B.F. Brouwer
Publication date
01-08-2012
Publisher
Springer-Verlag
Published in
The European Journal of Health Economics / Issue 4/2012
Print ISSN: 1618-7598
Electronic ISSN: 1618-7601
DOI
https://doi.org/10.1007/s10198-011-0318-y

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