Decision Filter: Cutoff Value

The cutoff value of your decision filter represents the minimum estimated promise of a therapy required before you would be willing to use it. Your cutoff value represents your level of skepticism. So exploring the effect of different cutoff values shows the effect of varying levels of skepticism on the outcome of your decision process and ultimately on the amount of benefit you get from your choices.

It may have occurred to you that a single cutoff value applied to all possible alternative therapies despite vastly varying characteristics is not how decision making really works. I agree. And in the last part of the presentation I will describe in great detail how you might modify the cut-off value separately for each therapy based on its particular characteristics. I also don't expect that you (or anyone) would actually use numbers to represent the promise of therapies they are considering and use a numeric cutoff to decide. Instead, it will be something of a gut feel of how much promise you require for a given therapy to accept it. Still, it is useful to consider the general effects of a high (skeptical) cutoff or a low (credulous) cutoff.

In this diagram the cutoff value used is shown as a black circle in the box in the lower left. The size of the circle represents the cutoff value. In this example the large circle means all therapies with promise that size or less would be accepted. Remember that small circles are the most promising therapies. So this diagram is an example of the effect of a very low cutoff value.

With a very low cutoff value, you would accept virtually any therapy. Thus the group of therapies selected is shown as the same as the group of therapies you are choosing from. In reality, since you probably can't use all therapies at once, if you are operating with a very credulous cutoff your are likely to just accept the first few therapies you encounter. If you accept that most alternative therapies are not promising but only a few are, then you can see that this strategy selects mostly unpromising therapies and does not maximize your odds of survival. If you actually believe that most alternative therapies are highly effective against cancer, then you might think that such a filter would be effective - you don't need to pay much attention to choosing a therapy if almost anything works. I wish cancer were that easy!

This CancerGuide Page By Steve Dunn. Copyright 1999 Steve Dunn
Last Updated June 22, 1999