In this chapter we will consider some further evaluation issues in a risky world. An important issue seldom touched upon in health economics is the value of information in a situation where a measure may have some irreversible effects. This kind of problem gives an extra dimension to the valuation issue. That is, how do we define and measure the value of the option to delay a decision when there is independent R&D going on which may reveal whether the consequences are in fact irreversible?

A second issue to consider is the health production function approach and further illustration of how the intertemporal version can be used to evaluate health changes. In particular, time used up in the production of health is now introduced, and the individual has a job so that his health status may affect the number of hours s/he works or the hourly wage s/he receives.

The final issue to be considered is an intertemporal model in which the survival probability is age-dependent but may also be affected through investment in health capital. In turn, the health production function is age-dependent. The model is used to define money measures of a parametric change (say, a medical treatment) in the health production function or in the survival probability. As an important by-product it is shown how to handle a death risk which depends on a state variable (health); it is easy to overlook the fact that such a problem is not a standard optimal control problem.