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

guide to all sorts of numbers, naughty and nice and I'm Tim Haafard.

Among many other things this year has shown us the importance of good robust data.

As Covid-19 spread around the world it was vital to track where it was, how many people it was

infecting and where it might go next. On more or less we've spent months reporting on data

inaccuracies and vacuums but what makes for good or indeed bad data.

A few weeks ago I spoke to Amy Maxman, senior reporter at the scientific

journal Nature about which countries are getting data collection right and which aren't.

We started at the top of the class with South Korea.

Every day they've got a report that goes up and they kind of vary but they've got a lot of

measures. They also have detailed reports on clusters so for example I just went to the one

that was yesterday and you can see that over the past two weeks they say 30% of the new cases

are contacts of cases that they had been following. 11% are travelers from out of the country

and 26% are in local clusters so the household contacts are in their own category and then there's

clusters. So then they have a list of the clusters that are happening. You know there's a sauna

that had 20 cases and they even detail it out. Five of those cases aren't people who went to the

sauna but they were associates of the people who were at the sauna. So they've got these really

detailed reports. Is what's good about that the fact that they have all this data or is it that

everyone has that kind of data but the South Koreans are making it publicly available and accessible?

It's both. So one is you know public health officials have the data so they are kind of getting a

sense of where do they have to drill down in their efforts instead of saying everybody we've got

an outbreak in this province let's everybody shut down all businesses shut down the schools

...