Use of different epidemiological metrics in COVID policy communications

Question

Many governments used different metrics to set and communicate their policies during different phases of the COVID-19 pandemic. To list just a few:

• The reproduction number (R).
• The incidence rate, usually per 100,000 people per week.
• The percentage of positive tests.
• The mortality, again usually per 100,000 people per week.
• The excess mortality.
• The infection fatality rate.
• Free hospital beds, as a percentage or absolute number.
• Free intensive care hospital beds.
• Free fully staffed intensive care hospital beds.
• Vaccination rate.

As a layman I can puzzle some of this out myself. Assuming an exponential growth function, the reproduction rate is simply the derivative of a normalized incidence. Hospital beds matter more at the peak of a wave, not at the start or tail. Widespread testing wasn't available early on, so tests were only used to confirm suspected cases. Later on, daily tests became possible. And so on.

Has any government attempted to explain the use of different metrics at different times to their general public in high-profile messaging rather than specialist-only webpages?

Answer 1

Generally speaking, metric selection and other minutiae of methodology are not communicated as part of the main public-facing channels (which is how I read "high-profile messaging" here). The general public is neither expert enough to make sense of such, nor are their specific needs served by it: these are communications which are intended to swiftly deliver actionable instructions or guidance as efficiently as possible. Optimizing for maximum signal and minimum noise means dropping the details that do not contribute to the communication of the bottom line.

The specialist-only web pages you identify are almost always still available to a curious member of the public, should they have sufficient subject-matter literacy and the spare time to commit to absorbing the information.

If someone is subject matter literate enough to notice the differences, but not enough to make sense of (or perhaps even locate) the more detailed information, that's where specific inquiries fill in: they can ask people more expert than themself on the matter, or they can end up reaching out through constituent services channels (e.g. calling their elected representatives to get an answer). The availability of interpreters for that kind of information is probably very poor, but filling the general-public facing channels with highly technical information will tend to drown out the message you're trying to send.