How I monitor an area, or dealing with clutter.
I have been spending significant amounts of time examining data for colleges. Only, I have very little visibility into what is happening directly on campus, just the schools dashboard. Fortunately, the schools are located in fixed geographic regions. For example, almost all Va Tech students live in Blacksburg in the Zipcode of 24060. And, the state gives the following data by zip code:
The number of cases and testing are cumulative numbers. But, by taking the time derivative (e.g., subtracting one day from the previous day), I can get the number of cases and tests per day. And from that, I can derive a metric of percent positive.
For Va Tech, this looks like:
For Va Tech, the mean is low, so I will notice an outbreak when it is 3 standard deviations above the mean. For 22040, that was at 8 cases a day, or 0.02% of the population.
In other places, there are either more pre-student arrival cases (noise) or non-student outbreaks (clutter). As an example of clutter, I will show the cases for Longwood in Farmville: