In XKCD 2295, "Garbage Math," Randall Munroe does a stellar job elucidating the uncertainty plaguing our ability to estimate when lockdown will end.
https://xkcd.com/2295/
The thing is, several key variables are unknown and attempts to estimate them produce "garbage numbers." These include:
What percentage of people have covid-19 antibodies
What percentage of people who have covid-19 antibodies are immune to the disease, and for how long
When we will develop a vaccine for covid-19
How long production of the vaccine will take after it is developed
When we will discover effective therapeutics for covid-19
How long it will take to ramp up their production
These variables produce a combinatorial explosion of scenarios for when the lockdown will end, and how long after that the crisis will pass. These scenarios are the reason we have a range of "estimates" – they're not estimates, they're scenarios.
If a and b, then x more weeks. If a, b and c, then y more weeks. If a and c, etc, etc.
These kinds of scenarios are a lot more common than predictions, but scenarios are usually presented (by governments, press and science communicators) as predictions.
In part, that's because our public discourse has little room for scenarios – but also, that's partly
why our public discourse has little room for scenarios.
