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How certain do people think a negative (or positive) COVID test result is? Is that affected by the info used to explain test results?
We tested info from NHS, CDC, and New Zealand’s page about test uncertainty against people who got no information… https://www.medrxiv.org/content/10.1101/2020.12.04.20243840v1
We tested info from NHS, CDC, and New Zealand’s page about test uncertainty against people who got no information… https://www.medrxiv.org/content/10.1101/2020.12.04.20243840v1
The NHS page gives categorical information with no uncertainty mentioned. CDC say a negative result ‘probably’ indicates… New Zealand have a page all about sensitivity and specificity.
We added a condition where we put some of the uncertainty information into the NHS’s wording
We added a condition where we put some of the uncertainty information into the NHS’s wording
When asked what chance the test recipient had of having COVID, those who saw the NHS wording were more likely to answer either 0% or 100% than those in any other group and those who saw the New Zealand wording were less likely to be so definitive.
Without any information – the control group – people were naturally cautious. They thought negative test results less reliable and trustworthy than positive ones and often took a precautionary approach to them.
When asked whether the test recipient, described as symptomatic, should continue to self-isolate even after a negative test result, though, those seeing the NHS wording were most likely to say ‘Completely disagree’, and those seeing the New Zealand wording least likely to.
Those who saw the New Zealand wording and who said he should self-isolate even after a negative result often cited the reason that the test result could be wrong.
Our experimental addition of some uncertainty wording to the NHS information helped people be less dogmatic in their interpretation of a negative test result, but didn’t have the same effect as the information provided by the New Zealand Ministry of Health.
We’d recommend the NHS add some caveats about the interpretation of test results – as even no information, or the CDC’s very slightly less definitive wording seemed better.
Partly inspired by the concerns of @mgtmccartney
