A Rotorua family sits down to dinner in late 2014. Their grocery bills for the year: $7,683. Twelve months earlier, that same household would have spent $15,317. That's not a typo. Rotorua's annual food spending just fell by half in a single year.

This isn't a gradual decline. For four straight years, Rotorua households spent between $14,500 and $15,300 annually on food. The figure barely moved: $14,492 in 2010, $15,309 in 2011, $15,295 in 2012, $15,317 in 2013. Then 2014 arrived and the bottom fell out.

To find a comparable figure, you have to go back to 1993. That's 21 years. A generation ago, when the average Kiwi was earning a fraction of today's wages, Rotorua households were spending roughly the same on food as they did in 2014.

What happened? The data doesn't lie, but it doesn't explain itself either. A 50% drop in food spending doesn't happen because people suddenly decided to eat less. It doesn't happen because prices crashed; national food price trends show steady increases through this period. Something fundamental changed in how Rotorua's food spending was measured or reported in 2014.

But here's what the number tells us regardless: food spending data in New Zealand is fragile. Regional figures can shift dramatically, not because household behaviour changed, but because methodology shifted, sampling changed, or data collection was disrupted. The Stats NZ food price index is invaluable for tracking long-term trends, but year-to-year regional comparisons can be treacherous.

For Rotorua residents who lived through 2014, the experience at the checkout didn't match this data. Nobody's weekly shop suddenly cost half what it did the year before. The collapse is statistical, not real. Yet this is the official record.

The lesson: when you see a number that defies lived experience, question the measurement before you question reality. Regional food spending figures are useful for tracking decades-long trends. But a single-year plunge this dramatic? That's a data story, not a household story.

Rotorua's 2014 food bill sits in the record books at $7,683. It's the lowest in more than two decades. But it's also a reminder that not every number in a dataset tells the story you think it does (Source: Stats NZ, food-price-index-detailed).