Using the retrospective ratios between number of early cases and number of confirmed cases in China (~25:1 before widespread testing and lockdown) and extrapolating to the SF bay area (~100 confirmed cases), a gathering of 30 people already has a ~1% of chance of an infected person present.
Using the retrospective ratios between number of early cases and number of confirmed cases in China (~25:1 before widespread testing and lockdown) and extrapolating to the SF bay area (~100 confirmed cases), a gathering of 30 people already has a ~1% of chance of an infected person present.
(lots of assumptions but exploring which ones are least likely to hold is interesting)