Market share of UK retail supermarket trade.
Ever wonder where Asda 21.7%, Aldi 8.9%, Sainsbury's 17.9% data comes from? AFAIK each one submits factual monthly sales data to an independent body that crunches the numbers confidentially. It works because those firms are honest and respectable and over time the sales submissions can be verified against published accounts and press releases. No doubt many other industries work the same way.
Can you imagine the pseudo taxi businesses operating that way? The dynamics of "disruption" alone don't lend themselves to such cooperation.
AC been there, done the crunching.
Biting the hand that feeds IT
