Models and Complexity

The NY Times alleges that the Government is to release the models today. We frankly have no idea what that means. The description, the results, the source code, the underlying methodology? Since it is the Government they also have no idea what they are doing.

Let's give a simple yet complex example. Namely how does one model the transfer of the virus. Consider the example below:

Here we have an example of person to person infection. The infected individual can infect an uninfected by two means. First by aerosolizing the virus and transferring by air directly. That could be stopped by a mask. However proximity and time continuity is essential for this path to function. Second, by secondary touching. Namely the virus transferred say by hand to a surface, then the second person must touch the surface at the right spot in the right time period and transfer to their hand and then to their face to start the process. Gloves and hand washing stops that transfer.

We now above show a model for this process. Namely each step has a probability and each step has a mitigation element. We can then estimate the probability of infection from one person to another at a specific time period in a specific table surface at a specific temperature. Lots of assumptions.

Then if we want a model we have to assume that there exists an ensemble of people al functioning in some statistically similar manner. I think one starts to get the point. Assume, assume, assume etc

The issues continue since how this happens in a NYC subway is not how this happens in Scranton, and less so say in Bangor. But, and this is critical, this simple example is at the very heart of the model.

Problems like this were considered a century ago when examining statistical thermodynamics. It became an element of Einstein's Nobel Prize winning paper on Brownian Motion. Unfortunately the application to pandemics is grossly wanting.

As the above NY Times article states:

The models used by the White House team are standard epidemiological tools but are not precise, as the results can vary widely depending on how closely people follow the guidelines. In other words, the assumptions built into the models can shape the results.

This is an understatement. Having designed and tested such models and examined hundreds of others, and also understanding some of the dynamics of this virus, the simple answer is that no one has a real clue. Yet the two steps shown above of distance and hand protection are the best we can come up with now. My grandmother, Hattie Kruger, told me this seventy plus years ago from here experience in dealing with TB and the Spanish flu in New York. She lived to 90, so believe your grandmother. Thanks Hattie!