I wonder if Edge Animate or Possibly Flash could help me to accomplish the following task which was put to me by a colleague at the University I work at. The following text is taken from his email to me...
I’m trying to create a little web based gizmo to illustrate epidemiology and public health concepts for undergrads and wondering if you can help.
The idea is to compare the effects of two different approaches to health risk. One approach is to try to reduce exposure to Bad Thing #1 which is known to kill 50% of all people who continue to be exposed to it over their lifetime. The other is to try to get those exposed to Bad Thing #1 to switch to Bad Thing #2 (mortality known to be lower, but not clear how much lower). The twist is that the health community is worried that people not already exposed to Bad Thing #1, will expose themselves to Bad Thing #2 if it becomes available (thus raising overall health risk).
So here’s what I want to do…
Step one: illustrate the danger of Bad Thing #1 based on the proportion of the population exposed and the mortality risk. This part should be easy.
I want students to input two numbers:
- What is the size of the adult population of your country/region (age 12 and over)? ___ [user input here]
- What is the proportion of that population currently exposed to Bad Thing #1? ___ [user input here]
The result of the calculation would produce a circle that represents the expected mortality from exposure to Bad Thing #1. The size of the circle could be fixed (that is, it doesn't need to be based on the user input – it just needs to be a circle that can be changed in size based on subsequent user input).
OK, so now the student is staring at a circle. It would be nice if the circle contained the number of expected deaths, but that’s not essential, it just represents the number of expected deaths (population * exposure * .5).
Now, I want the students to answer three questions.
First, I want them to estimate how much less risky/safer Bad Thing #2 is than Bad Thing #1. If we assume #2 can’t be any more harmful than #1, this scale should range from 0% safer to 100% safer (perhaps in 5% increments if it can’t be more exact).
Second, I want them to estimate what percentage of people currently exposed to Bad Thing #1 could be convinced to switch to exposing themselves to Bad Thing #2 instead (i.e., stop exposure to #1 entirely, but fully expose themselves to #2). Based on this estimate, I want to show how much smaller the circle would be (number of expected deaths) if said percentage of #1 people switched to #2. When they enter this number (or push a slider), I want them to see the circle shrink (or a comparison circle shrink – I dunno).
Finally, I want them to estimate what percentage of the population who are not currently exposed to Bad Thing #1, might somehow find themselves exposed to Bad Thing #2. But this needs to be based on the proportion of the remaining adult population from the initial calculation at step 2 above (i.e., those not exposed to Bad Thing #1).
Now I want the circle to grow as they increase their estimate, but of course it has to be constrained by the size of the previously unexposed population and the risk of Bad Thing #2.
At the moment, I’m flummoxed about how to pull this off visually for the students.
For example, let’s imagine we have Drug A and 20% of the adult population is using it with a 50% mortality rate. If the student inputs “30,000,000” for the population and 20% for Drug A use, we get a circle representing 6,000,000 users of Drug A. If we know that Drug A has a 50% mortality rate, we get a circle representing 3,000,000 dead people.
If students then says that Drug B is 50% safer than Drug A, then we know that we can expect 30,000,000 * .2 * .5 *.5 = 1,500,000 deaths.
Showing a circle that shrinks from 3,000,000 to 1,500,000 is nice. Having a slider that illustrates how death rates change as risk increases/decreases is nice. Maybe I could figure out how to do that, but I’m old and the dementia is creeping…
But the hard part is figuring out how to include death rates if Drug B starts being used by people who don’t already take Drug A.
If 80% of non-Drug A using people start taking Drug B which we think is 50% safer (.25 mortality rate), then how many additional deaths should we expect?
At some combination of Drug A users switching to Drug B, and Drug B being __% safer to use and non-Drug A users taking up Drug B, we might end up with the same number of deaths. That’s the point I’m trying to illustrate.
Does that make sense? Is it possible to implement using a web interface – especially one that includes sliding scales and growing / shrinking circles?