The UK currently has 1,657,270 positive cases of COVID-19

[Ms. Toad]

50. A sample is presumed to be biased,

unless it is carefully constructed to avoid bias. That is statistics 101. You, so far, have not demonstrated that the tested population was carefully constructed to avoid bias.

No one is suggesting they don't test "a variety of people in a variety of ways." That isn't what matters to create a representative sample. What matters is that the mix in your sample matches the mix in the population. If it doesn't, you can't just just calculate the positivity rate of the whole by simple multiplication. It is always up to the person insisting that is possibl to demonstrate that the mix is truly representative.

No one, not a single person in this thread, is suggesting throwing out testing data. What we are telling you is that until you prove the sample was representative of the population of the UK, it is statistically invalid to suggest that all you have to do is to multiply the ratio of positive to testec by the population of the UK to determine how many people are currently positive.

You obviously are clueless as to sample bias, and are unwilling to take basic educational steps to find a clue.

We have nothing more to discuss until you - the proponent of a simple proportionality calculation - demonstrate such an extension is valid by providing the mix of those being tested demonstrate it matches the mix of the population as a whole.