Hello and welcome to more or less on the BBC World Service. We are your weekly guide

to the numbers all around us in the news and in life, and I'm Tim Haferd.

This week we're looking at how a well-intentioned TikTok video disrupted around 4,600 academic

studies.

It used to be that recruiting people to take part in research meant rounding up a group

of students to take part in a task, or asking members of the public on the street to answer

questions.

But the internet has changed all that, just like it changed the world of dating with apps

such as Tinder.

If you're an academic who needs some participants for a study, nowadays you've got online.

Professor Ayal Pererle of the Hebrew University in Jerusalem explains.

The one that most people know and have used is Amazon Mechanical Turk.

It was not built as a website for academics.

It's targeted to commercial organizations and firms to crowdsource tasks in what they

call micro-tasks.

And at some point researchers from academia realize that they can actually use this platform

and have their surveys actually function as a micro-task that the worker completes.

So what are these micro-tasks that people get asked to do on a Turk?

Imagine that you have a furniture company.

You have a lot of products and you want to create a catalog.

And you have a lot of pictures of your products and you want to categorize them correctly.

If you put one person on the job, it might take them several days to go through all the

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