All tests have a false positive and a false negative rate.
just remember that RATs and PCR test for different things - one looks for presence of a viral protein, the other looks for RNA - they don’t necessarily correlate.
Fully aware of the differences in molecular target. Was saying that PCR false negative generally accepted to be lower than 10%
Helpful lay article here which explains the maths of why single RAT+/PCR- is still more likely to be truly positive
The reason for these results has yet to be confirmed – but maths may explain the phenomenon.
www.google.com
However my situation is different as have had repeated tests. Given the accepted specificity of a RAT is higher than the sensitivity of a PCR on simple maths that would suggest I am more likely to be positive.
However, with repeated discordant tests we are dealing with very small likelihoods that either is wrong on a mathematical basis
Wrong Abbott RAT+ x4 is (~0.005^4) less than one in 100 million.
Wrong PCR- x3 plus Innohep RAT-×1 is less than 1 in 10000.
However, with such small probabilities, saying one is higher than the other is pretty meaningless
In this circumstance it seems much more likely that there is something "wrong" with how one of the tests interacts with me. I suppose it's fair to say the answer as to which one is not certain either way
(This does ignore the pre-test probability-I am asymptomatic which makes me more likely to be negative but on the other hand my children had Covid which makes me more likely to be positive)
www.tga.gov.au
www.abc.net.au
