Under a tasteless image of a woman grimacing in pain, BBC Scotland today is using the news on new testing for endometriosis to suggest waiting times are longer in NHS Scotland than in NHS England based on the average.

Using this measure, we hear it’s 10 years and 2 months in Scotland but 9 years and 4 months in England.

There’s a problem.

This is not based on Public Health Scotland officially checked and published statistics but, rather, it’s based on data collected by the charity Endometriosis UK.

What’s wrong with that?

Several things make the figures unreliable and, if BBC Scotland did its job, they’d be presented as such.

First, it’s a self-reported, ‘squeaky-wheel’ survey. So there’s a danger of recall bias where respondents do not remember the exact symptom onset, years later and there’s selection bias where people with worse or longer experiences are more likely to respond distorting the average.

Second, sample size for Scotland isn’t broken down so we can’t tell if it’s big enough or representative enough to be compared with the UK sample.

Third, self-reported diagnoses aren’t clinically verified in the survey though respondents say they have a formal diagnosis. Official data relies on coded clinical records.

Fourth, respondents may interpret “when symptoms started” differently, or emphasise negative experiences when answering a patient charity survey.

BBC Scotland, as ever, fail to meet their own editorial standards criteria requiring them to check claims and to never rely on just one source.