Here's a number that should make you stop and ask questions: Rotorua's food price index sat at 15,317 in 2013. One year later, it was 7,683. That's not a 50% reduction. That's a statistical impossibility.

Food prices don't halve overnight. They don't even halve in a decade. So what happened in Rotorua in 2014?

The trajectory tells you something's off. From 2010 to 2013, Rotorua's food price index held remarkably steady: 14,492 in 2010, climbing gradually to 15,309 in 2011, then plateauing at around 15,300 for the next two years. These are normal movements. Small fluctuations. The kind of shifts you'd expect in a regional food market.

Then 2014 arrives and the number gets cut in half.

This isn't about cheaper groceries. This is about a methodology change, a recalibration, or a data collection problem that nobody explained to the public. And that matters, because when the numbers measuring your cost of living suddenly shift like this, you lose your ability to track what's actually happening to prices over time.

Think about what this means for anyone trying to understand how Rotorua's food costs have changed over the past decade. You can't. The data has a black hole in the middle of it. You can't compare 2014 to 2010 without knowing what changed in the way Stats NZ counted these prices.

This index now sits at its lowest point in 21 years. You have to go back to 1993 to find a comparable figure. But that comparison is meaningless if the measurement system changed halfway through.

The broader point: we make decisions based on these numbers. Policy gets written around them. Wage negotiations reference them. Families trying to budget use them to understand whether their grocery bill is normal or whether they're being squeezed harder than everyone else.

When the data suddenly jumps or collapses without explanation, all of that becomes guesswork. And in 2025, when every dollar in a household budget is accounted for twice over, we can't afford guesswork about what food actually costs.

Rotorua deserves to know what happened to its food price index in 2014. So does the rest of New Zealand.