On Friday, I got a call from daycare. Ro already had a runny nose. Now he was coughing.

He has asthma, so it's not that unusual for anything he's fighting to go straight to his chest, but still: "please come and pick him up." I pick him up, we get tested at 5.30pm that evening.

The nurse says - even if the result is negative, if you were self-isolating, you still need to self-isolate. "Why?" I ask.

"Because it's only 70% accurate."

Huh. 🤦‍♂️

That would be a false negative. It gives you a negative result when really the underlying truth is that you're positive.

A false positive is the positive result when really you're actually negative.

As you can see by the fact that we're using these tests, having false positives or false negatives is not necessarily a deal-breaker.

🤔🤔‍🤔

A test that gives false positives can still be relied on if it gives you a negative. You know for sure you DON'T have it.

A test that gives false negatives can still be relied on if it gives you a positive. You know for sure you DO have it.

And tests that give both??

Well, it needs to have something else redeeming. Maybe it's super quick or super cheap and can be used as a diagnostic or to allow far more people to take the test. Maybe it's painless and the more reliable test is invasive.

Or maybe it's the only test we got.

Reminds me of how lawyers sometimes view their job. Have a shitty day, this job sucks. Win a case, they were made for this job. We're testing it every day, and a lot of these are false results.

Which doesn't mean it can't be used as a diagnostic, but it DOES mean that you need to bring extra awareness. Awareness that they could be false results.

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Coughing all over your false negatives 🤧