Does PayPoint cause footfall?

There is a correlation between the number of storks’ nests found on Danish houses and the number of children born in those houses, economist Tim Harford wrote in the FT last month.

“Could the old story about babies being delivered by storks really be true,” he asked.

“No. Larger houses have more room both for children and for storks.”

The correlation does not cause the outcome.

This distinction is usefully made at a time when retailers in the UK are wrestling with the thorny questions of the benefit of footfall drivers, including the controversial PayPoint service.

Is it that users of PayPoint spend more because the service is available in store or is it that PayPoint is convenient to shoppers who were planning to spend more anyway?

Surely PayPoint seeks to be located in stores which have the correct location more than those stores with the right locations seek to have PayPoint in their stores.

Resolving this distinction is always likely to be determined in favour of whoever pays for the research.

As Mr Harford concluded of statisticians, critics claimed their consulting fees caused their scepticism. But is was just as likely that their scepticism caused the consulting fees.

I suspect the correct answer will always be in the eye of the beholder.