Coronavirus Event Risk Assessment Tool

Kind of a cool map-based tool for assessing chances of encountering an infected individual at an event of size x. There are sliders to set the event size and 2 choices for "ascertainment bias." In some ways, that's the most interesting bit of information here. The "ascertainment bias" is the estimate of how much current infections are being undercounted by confirmed tests. The default level is set at 5:1, which is apparently the latest scientific consensus. So currently, it is believed that for every diagnosed case there are four more that are not formally diagnosed. A few months ago, that ratio was 10:1 (which is the other setting choice on this map). 

Because of the way probability statistics work, the results are a little startling. Right now, in Hennepin County, the chances of encountering an infectious coronavirus carrier in a group of 10 random people is about 34%. In a gathering of 50 people the probability rises to 88%. 

Wow. That is sobering. Not surprising that weddings, funerals, church services, and bars have been spreading the virus so fast.