People love lists. That’s why the Financial Times’s business education rankings are pored over, debated and dissected. We know this because every time we publish a set of rankings, our website traffic jumps.

For anyone who cares about business education, tracking how valuable a qualification from one school might be relative to another is absorbing and entertaining, not to mention sensible. The average cost — including lost earnings — of an MBA is more than $200,000, according to FT research.

My team at the FT is responsible for these massive data projects. But recent studies into the psychological effects of such lists has caused me to worry about how even highly numerate people interpret our rankings. The minute we see a list, it seems, we forget everything we know about basic maths.