To get a more accurate estimate for Person Risk, we can actually add up the risk (in microCOVIDs) of their recent behavior. Remember, a single microCOVID represents a one-in-a-million chance of getting COVID.
The Advanced Method is to add up the risk of each individual activity that person has done recently.
The Risk Tracker is a tool that can help you add up activities in the Advanced Method.
Just like you can calculate this for each of your actions, you can also calculate it for your friend’s actions, using the same formula:
Cost = Activity Risk ⨉ Person Risk
We can do this by looking at all of their activities between 2–9 days ago[1] and determining the risk of each individual activity. Or if they do the same things every week, what does their typical week look like?
This is an advanced method because it requires asking about and calculating the risk of each of your friend’s recent or typical errands, hangouts, and other activities. And you might have to ask about your friend’s contacts too!
The advanced method hinges on getting an accurate picture of all of your contacts' activities and risks. This requires examining their lives in more scrutiny than you may be used to in normal times. To help, we've developed a list of questions to ensure you are thorough in assessing their risk.
We think about risk in three categories: socializing, errands, and work. To calculate total Person Risk using the advanced method, you can add these three categories together, as follows:
Person Risk (Advanced) = Socializing + Errands + Work
Note that this formula uses addition, whereas everything else we’ve done until now has been multiplication.
For socializing, just estimate each social activity in microCOVIDs (using “Cost = Activity Risk ⨉ Person Risk”) and add them together. This is the place to count the exposure from all their household members as well.
Errands include grocery shopping, transit, and other public settings. These can be harder to estimate individually; we have some guidelines in the Q&A.
Work is modeled just like the above socializing and errands, and you would ask similar kinds of questions: how many people is this person sharing indoor air space with? For how many hours per week? What is their risk profile like?
Though you can do Advanced Method calculations on your own, the Risk Tracker was designed for that very purpose. It is a helpful tool for both individuals and households/pods who want to manage their risk.
The best way to understand how to apply the Advanced Method is through an example. See the next section for a detailed example.
The 2-9 day window is an approximation for people who keep relatively constant schedules or maintain a similar level of risky behaviors week over week (for instance, by using microCOVID to track their own activites). If this is not a good description of the person's behavior (e.g. they recently took a flight, went to a party or indoor restaurant, or had contact with someone with COVID), it is necessary to count up all their activities from the last 2-23 days (3 weeks). Events past 5 days have diminishing effects on their riskiness, which makes this method difficult to do by hand. The Risk Tracker handles this calculation for us. For details on how this is derived, see Research Sources. ↩︎