I’ve written before about how the statistic “50% of all clinical trials are unpublished”, much beloved of the All Trials campaign, is simply not evidence based.

The charity Sense About Science, who run the All Trials campaign, also run a rather splendid website called “ask for evidence“, which encourages people to ask for evidence when people make dodgy claims.

So I used Sense About Science’s website to ask for evidence from Sense About Science for their claim that 50% of all trials are unpublished.

To their credit, they responded promptly, and pointed me to this article, which they claimed provided the evidence behind their claim.

So how well does it support their claim?

Interestingly, the very first sentence states that they don’t really have evidence. The first paragraph of the document reads as follows:

“We may never know the answer to this question. In some ways, maybe it doesn’t matter. Even one clinical trial left unreported is unacceptable.”

So if they don’t know, why are they making such a confident claim?

As an aside, they are of course spot on in the rest of that paragraph. Even if the proportion of unpublished trials is substantially less than 50%, if it’s greater than zero it’s still too high.

They go on to further emphasise the point that they really don’t know what proportion of trials are unpublished:

“It is clearly not a statistic, and we wouldn’t advocate trying to roll up the results of all the studies listed below to produce something spuriously precise.”

They then go on to explain the complexity of estimating the proportion of unpublished trials. It certainly is complex, and they give a good explanation of why. It’s not a bad document, and even includes some studies showing much higher rates of disclosure that they don’t admit to on their main website article.

But if they understand, as they clearly do, that the claim that half of all trials are unpublished is spuriously precise and that it would be wrong to claim that, why do they do so anyway?

Not only do they make the claim very confidently on their own website,  the claim also often appears in the very many articles that their PR machine churns out. These articles state it as fact, and do not acknowledge the problems that they describe in their background document. You will never see those articles citing the most recent research showing greater than 90% disclosure rates.

This still seems dishonest to me.

Those of you who have known me for some time will know that I used to blog on the website of my old company, Dianthus Medical.

Well, Dianthus Medical is no more, but I have preserved the blog for posterity. You can find it again at its original home, dianthus.co.uk. If by some remote chance you happen to have any links to any of the old blogposts, they should work again now. All the blogposts have their original URLs.

The Dianthus blog no longer accepts comments, but if you have an urgent need to leave a comment on anything posted there, you are welcome to leave a comment on this page.

Well, 2014 has been an “interesting” year for me. The company that I’d run for 15 years, Dianthus Medical, went bust in July, and I rather suddenly and unexpectedly found myself unemployed. That was not a fun experience.

Happily, I didn’t stay unemployed for long, and in the autumn I started a new job. I must confess to having been a bit nervous about this after having been my own boss since the days when we all used to think Tony Blair was one of the good guys. But I needn’t have worried: my new job has turned out to be a real joy.

Running a business was pretty damn hard work. The silver lining of the cloud that was my business going tits up is that I no longer have to worry about all that business stuff: dealing with endless government-mandated red tape, chasing customers who don’t pay on time, trying to find new business, and all that sort of thing. Now I can just get on with doing all the interesting statistical consultancy that I enjoy.

You may remember that I used to write a blog on the Dianthus Medical website. That site is sadly now defunct, but I do have a backup of all the blogposts and I will get round to putting them back on the internet one of these days.

But anyway, after a little break from blogging while I sorted my life out, I’m back. I hope you’ll come back and visit my new blog and see what interesting things from the world of statistics, medicine, and science move me to write something.