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We strive to be the golden thread leading you through the labyrinth of statistics, bringing you out to the surface

into the light of numerical clarity.

Then I'm your statistical Ariadne Tim Harford.

In early January, the UK's Office for National Statistics, known as the ONS,

published data on productivity in the G7, seven rich countries including the UK, Germany, the US and Canada.

With the easing of lockdown restrictions across countries, output per hour worked growth was positive for all G7 nations in 2021.

With the UK experiencing the largest year on year increase, 22%.

Wow, 22%. It sounded like good news for the UK in particular, but also for the other nations,

some of which also experienced double digit increases in productivity growth.

But just 12 days later, the ONS issued a correction.

The previous version suggested that the UK output per hour worked in 2021 had the fastest growth of the G7 countries.

This has now been corrected to the second slowest.

When you looked deeper at the correction, you realised just how big it was.

The UK's productivity didn't grow by 22%, it fell by 1.8%.

And it's a similar story for other G7 nations. Canada's productivity didn't grow by 18%, it went down by 6%.

Italy's wasn't 21%, it was minus 1%. So what on earth went wrong?

The ONS told us that they used Microsoft Excel to calculate the figures that these growth rates are based on,

but they made a critical mistake. They essentially misalligned two columns,

...