"Time for health" : the development, validation and comparison of instruments to value improvements in health
This work begins by describing a general theory of value which embraces many of the commonly used valuation techniques that have been developed by economists (the time tradeoff, the standard gamble and willingness to pay). These techniques share the common characteristic that each expresses value in terms of a sacrifice that people are prepared to make in order to achieve the benefit being valued. Here, those benefits comprise improvements in health. In the time tradeoff, the sacrifice used to express the value people would attach to an improvement in health, is the amount of time they would give up to obtain it. Hitherto this technique has usually asked people to accept a premature death as the payment for better health. In the standard gamble, the most commonly used sacrifice that people are asked to make is a risk of death in exchange for better health. With 'willingness to pay', people are asked to value health in terms of the amount of money they would exchange for better health. Empirical evidence is produced from three major studies, involving 4739 respondents. These studies confirm that two health valuation techniques (the standard gamble and the time tradeoff) do indeed appear to be more closely related to each other than to other valuation methods, not based within the economic theory. Further work establishes the validity of an adaptation of the time tradeoff technique to overcome some of the principal disadvantages of the method as it has usually been applied hitherto. This adaptation asks people to value health by giving up time during much shorter and more immediate time intervals.