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definition of combined risk score

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jensjensenjens 2020-06-20 16:18:04 +02:00
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solution_architecture.md
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@ -217,7 +217,7 @@ Each of the four risk categories (days since exposure, exposure duration, weight
According to the [documentation of the framework](https://developer.apple.com/documentation/exposurenotification/enexposureconfiguration), "the attenuation is weighted by the duration at each risk level and averaged for the overall duration". In order to incorporate the time spent within the ranges of attenuation buckets mentioned before, each of those three buckets is assigned a weight value as shown in *Figure 13*.
The individual time values are multiplied with their according weight (*weight_1*, *weight_2* and *weight_3*).
Their sum and a default bucket offset (called *weight_4* in *Figure 13*) forms the *Exposure Score*.
Finally, the maximum of the *total risk score* over all the considered events, i.e. the largest risk score, is normalized and then multiplied with the above exposure score. The resulting product of the *exposure score* and the *normalized maximum total risk score* is then denoted the **combined risk score**.
Finally, the maximum of the *total risk score* over all the considered events, i.e. the largest risk score, is normalized and then multiplied with the above exposure score. The resulting product of the *exposure score* and the *normalized maximum total risk score* then forms the so called **combined risk score**.
The combined risk score is used to determine which defined risk level should be displayed to the user, e.g. “low risk” or “high risk”. For this decision, [app-defined thresholds](https://github.com/corona-warn-app/cwa-server/blob/eb8be6c3e9c723c62c619784e41889d10054cc93/services/distribution/src/main/resources/master-config/risk-score-classification.yaml) for the individual risk levels apply.
As the values above are multiplied with each other, a single category with a risk score of 0 means that the overall risk score is also 0.