While Wairarapa communities struggle with storm-damaged infrastructure cutting them off from livelihoods, there's a different kind of disconnect happening in New Zealand's data — one that makes it harder to understand what's actually happening to the cost of living.

Stats NZ's food price index for Whanganui shows something that should be impossible: food prices appearing to drop by half between 2013 and 2014, plunging from 15,641 to 7,798. That's not a typo. That's what the official figures say. (Source: Stats NZ, food-price-index-detailed)

Here's the problem: nobody in Whanganui experienced a 50% drop in their grocery bills in 2014. Inflation didn't reverse. Supermarkets didn't halve their prices. Something changed in how the data was measured or reported — likely a methodological shift or rebasing of the index — but that context isn't visible in the raw numbers.

This matters right now because New Zealand is obsessed with infrastructure. The government just unveiled its first national infrastructure plan, promising billions for roads, water, and electricity. But data infrastructure — the systems that tell us what's actually happening in the economy — gets no headlines when it breaks.

And it breaks more often than you'd think. Between 2010 and 2013, Whanganui's food price index climbed steadily: 14,652 in 2010, then 15,404, then 15,641. That's a normal trajectory. Then it falls off a cliff to 7,798 in 2014 — the lowest level in 21 years, back to 1993 levels, according to the dataset.

Except 2014 wasn't remotely like 1993 in terms of purchasing power. These are nominal figures, not adjusted for inflation. The New Zealand dollar in 2014 bought far less than it did in 1993. A food price index of 7,798 in 2014 doesn't mean the same thing as 7,798 in 1993 — but without the methodological footnotes, the numbers appear to tell a story that never happened.

This isn't about Whanganui. It's about how we measure the cost of living across New Zealand. When official statistics have discontinuities this large, it becomes nearly impossible to track long-term trends, compare regions, or make policy decisions based on evidence. You can't plan infrastructure — whether roads or social support — if you can't trust the baseline data about what people are experiencing.

The retail crime taskforce recently came under fire for renting expensive office space against advice. But at least that's visible waste. Broken data systems cost us in ways we never see: missed trends, wrong assumptions, policies built on numbers that don't reflect reality.

Somewhere between 2013 and 2014, the way we measured food prices in Whanganui changed. The data shows it. The methodology notes should explain it. But if you're trying to understand whether your region is getting more or less affordable over time, you're on your own.