450 ways to measure a feeling

There's a number from a study published last week that we haven't been able to put down.

The WHO's European office reviewed 75 studies on how we measure mental health across the region. They were trying to answer a question that sounds simple until you sit with it: when researchers say someone is "doing better" or "doing worse," what are they actually counting?

The answer was 450 different things. Four hundred and fifty distinct indicators, scattered across the literature, often measuring the same human experience in incompatible ways. As one of the WHO advisers put it, if a researcher in Finland and a researcher in Bulgaria are both studying depression in teenagers but using different thresholds and definitions, you can't meaningfully compare what they find. Now multiply that by 450.

Reading it brings up two feelings at once. The first is the obvious one — that's a problem, and a big one. The second is quieter and more personal, because it's the exact problem that sits at the heart of building a wellbeing app like Nagi: how do you put any kind of measure on something as moving and personal as how a person is doing?

Why this is harder than it looks

It would be easy to read "450 indicators" as a story about disorganisation, as if everyone just needs to get in a room and agree. But the WHO report is honest about why that's not the whole picture, and that honesty is worth sitting with.

Mental health is genuinely hard to measure. Experiences are subjective. The same symptom shows up differently across cultures. Our understanding of what wellbeing even is keeps evolving. For some conditions there simply isn't a universally accepted definition, let alone a universally accepted ruler. So the 450 indicators aren't only a mess — they're also a reflection of how varied and slippery the thing we're trying to capture actually is.

That tension — between wanting one clean number and respecting how different everyone's inner weather really is — runs through this whole field. The WHO's conclusion wasn't "pick one and force everyone to use it." It was subtler: we need measurement that's flexible enough to reflect how different people are, while still being consistent enough to compare. Hold both. Don't collapse one into the other.

The scale underneath the numbers

It's worth saying plainly why any of this matters. The same study notes that more than 143 million people in the WHO European Region were living with some form of mental health condition in 2021 — roughly one in six. And prevalence is estimated to have risen about 25% compared to before the pandemic.

When the data is fragmented, those people pay for it. One of the advisers said something that stuck with us: behind every gap in the data is a gap in the response, and behind every gap in the response are people who didn't get the support they needed. Measurement isn't an academic nicety. It's the difference between a system that can see you and one that can't.

What we've tried to do with Nagi

Nagi doesn't solve a problem the WHO has flagged at the scale of an entire continent — it doesn't, and we'd be wary of anyone whose app claimed it did. But this study sits very close to a decision made early in building Nagi.

We didn't want to bolt together a random handful of questions and call it a wellbeing score. So we built our own measure — the S8 — and rather than just trusting that it works, we're running a formal validation study to find out whether it actually holds up. That's slower and less glamorous than shipping a number and moving on. But the WHO report is basically a region-sized argument for why the slow version is the right one. A measure you haven't checked is just a guess with a decimal point.

The other half of it is more personal, and it's really why Nagi exists. Population-level measurement is one thing. But there's also the quiet, private version: just noticing how you are doing, over time, in a way that's actually yours. That's what the four-tap check-in is for. Not a diagnosis — Nagi doesn't do that, and isn't a medical device — just a gentle, repeatable way to put down how today felt, so that over weeks you can see a pattern you'd never have spotted from inside a single hard evening.

The takeaway we keep coming back to

You don't need 450 indicators to take your own wellbeing seriously. You need one honest, consistent way of checking in, and the patience to do it more than once.

That's the strange comfort in a dense public-health report about data standards. The experts are wrestling with exactly the thing each of us wrestles with privately: how do you put a number, or even a word, on something as personal as how you're doing? The answer isn't to give up because it's imprecise. It's to measure gently, measure consistently, and let the pattern — not the single bad day — tell you the truth.

If you'd like a calm, private place to start noticing your own patterns, Nagi is at nagiandme.com — no name, no email. First week free.

— The Nagi team

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Source: New study reveals gaps in how mental health is measured in European Region, WHO/Europe, 25 June 2026. Underlying scoping review: Mapping of mental health indicators in the WHO European region, BMJ Health & Care Informatics.

Nagi is a mental health companion, not a medical device, and nothing here is medical advice. If you're struggling, please reach out to a professional or someone you trust.