The Cochrane Colloquium Challenge 2019 - That was emotional!

The Cochrane Crowd challenges are always fun. People from around the world log in to Cochrane Crowd and assess titles and abstracts, deciding whether they are describing a randomised trial or not. Here’s an example:

It’s slightly odd perhaps just how fun it is; how with every challenge the race towards the finish line is a guaranteed adrenalin rush. This latest challenge was no exception.

We got off to a very strong start. Even just after two hours, I knew we’d have to change the target of 48,000; by the halfway point we had already reached that. Picking a new target is always a slightly risky business. Whilst it is good to aim high, setting a target too high and then missing it by some way would be a little deflating. I’ll admit a part of me thought, we’re all tired, and it’s the end of the year: why don’t we just go for something totally achievable and sit back and relax. But no, that’s not what we do in Cochrane Crowd!

We like to push ourselves to the limits: in that case, let’s aim for 100,000 classifications in 48 hours! As soon as I twitted this new target, I regretted it. Time seemed to suddenly speed up and for a while we struggled to keep pace, but then just as I was considering how to reduce the target, the numbers starting climbing up and up. At 97,000 classifications I knew we’d make it (just) and I’ll admit I shed a little tear. We ended on 100,724 classifications. Never underestimate the Cochrane Crowd community.

In context: we did more in 48 hours, than we did in the first six months of the Embase project. We launched the former version of Cochrane Crowd (the Embase project) in February 2014. Back then it took us six months to reach 100,000 classifications. Nowadays, it takes around 2-3 months to notch up 100,000 classifications. Doing it in 48 hours is therefore pretty darn impressive.

It was a truly international effort: 165 people based in 47 countries took part and collectively identified just over 6750 reports of randomised trials from 100724 total classifications made. A special thanks needs to go to the challenge’s top three screeners who devoted a significant amount of time to the challenge. A very well done to: Abhijit Dutta, Nikolaos Sideris and Brian Li.

This was a special challenge, designed to run alongside a very special Colloquium: Cochrane’s first virtual Colloquium:

If you are new Cochrane Crowd but looking for a way to contribute to the work of Cochrane that is flexible and fun, then do take a look to see if Cochrane Crowd is for you: It’s a thriving and clearly very energetic community! And if you have any questions or queries please don’t hesitate to get in touch with me (Anna) or my brilliant team mate Emily at

Finally, thank you to everyone who was able to join in with this latest challenge and indeed any of our previous challenges.

Together we are making a difference.

Anna and Emily