Methodology Β· how we check

How we test claims.

Atlas KaaTai tests sweeping claims against open data β€” across all 400 German districts, open-ended. We confirm and we debunk. Here is how we calculate, where the method reaches its limits, and how you can verify every result yourself.

πŸ“ To the principles 🏠 Overview

How our fact-checks come about β€” step by step Β· ← Overview

In short: we measure how strongly two variables move together across the districts, test the result against confounders, and label it honestly as true, partly true or not true. Every map is yours to open.
What we do β€” and what we don't

We take a sweeping claim of the kind you hear every day ("Where there's a lot of X, there's a lot of Y") and test it against data for all 400 German districts.

Our role is that of the referee: we test claims from every political direction, confirming them just as readily as we debunk them. We have no camp β€” only data.

Importantly, we describe patterns between regions; we do not judge people or parties. "In districts with feature A, feature B tends to be higher" is an observation about regions, not a verdict about individuals.

The metric: correlation (r)

We use Pearson's correlation coefficient r. It measures how strongly two variables rise or fall together across the 400 districts β€” and in which direction.

  • r = +1 β€” perfect alignment: where one is high, the other is high.
  • r = 0 β€” no linear relationship.
  • r = βˆ’1 β€” perfect opposition: where one is high, the other is low.

As a rule of thumb: |r| from about 0.2 is a weak, from 0.4 a moderate, from 0.6 a strong relationship. We state the r value openly in every fact-check β€” you don't have to take our word for it, you can recompute it.

The verdict β€” true / partly / not true

Every fact-check ends with one of three verdicts:

trueA strong relationship in the claimed direction β€” one that holds even after removing obvious confounders.
partlyThere is a relationship, but weaker than claimed or largely explained by another factor.
not trueNo relationship β€” or even the opposite of the claim.

The verdict always refers to the sweeping wording. "Partly" doesn't mean "who cares"; it means the simple story falls short.

The three limits we always keep in mind
  • District β‰  person (ecological fallacy). A map shows averages across regions, not individual people. A district-level relationship implies nothing about any specific person.
  • Correlation β‰  causation. Two variables occurring together does not mean one causes the other. Cross-sectional data show patterns, not chains of cause and effect.
  • Confounders. Urbanity, age or wealth can pull two variables up at the same time and create a spurious link. Where it matters, we remove such factors using partial correlation and report what remains of the relationship.
The confidence score β€” how reliable is an indicator?

For every active indicator, Atlas shows a confidence score (5–95%). It makes transparent how reliable the regional statement is β€” providers like Microm or Sinus don't publish such figures; we do.

The score combines two quantities, computed live across all areas of the active level (cells, municipalities, districts, constituencies or federal states):

  • Sample size n β€” areas with a value: n β‰₯ 200 β†’ 50 points Β· n β‰₯ 50 β†’ 30 Β· below β†’ 10
  • Dispersion β€” coefficient of variation Οƒ/|mean|: ≀ 0.35 β†’ +40 points Β· ≀ 0.8 β†’ +25 Β· above β†’ +10

Interpretation: High β‰₯ 70% Β· Medium 40–69% Β· Low < 40% ("caution"). With two combined indicators (bivariate mode) the minimum of the individual scores applies. Also shown: n, Οƒ and the P5–P95 spread.

Exception β€” absolute counts (population, persons, buildings): their large dispersion is real settlement structure β€” a village cell next to a city cell β€” not data uncertainty. For these, Οƒ does not enter the score; it derives from n alone (β‰₯ 1000 β†’ 90 Β· β‰₯ 200 β†’ 75 Β· β‰₯ 50 β†’ 50 Β· below β†’ 25), and the box marks the indicator as an "absolute value".

Important: the score measures the reliability of the aggregate, not the hit rate per person. A score of 85% means the regional differences are statistically stable β€” not that 85% of people there match the profile (ecological fallacy).

Neutral indicator names β€” and what's behind them

Some indicators carry neutral marketing names in the Atlas so that maps work in demos and campaign contexts without misreading. The data itself is unchanged official statistics β€” here is the translation:

  • International milieu = share of foreign nationals or residents with foreign citizenship / migration history / born abroad (Census 2022, specified in the label suffix)
  • Price-sensitivity index = share of low-income households (INKAR)
  • Premium affinity = share of high-income households (INKAR)
  • Senior share = share of population aged 65+ (Census 2022)
  • Traditionalist / progressive / ecological milieu = second-vote share of AfD / LINKE / GRÜNE (federal election 2025 or European election 2024)

The exact technical term always appears in the indicator's tooltip ("Fachbegriff: …"). The "Fachbegriffe anzeigen" link in the confidence box (or the URL parameter ?labels=fach) switches back to the original names at any time.

Where the data comes from

We use exclusively open, freely licensed official data (DL-DE 2.0 or ODbL):

  • Census 2022 (Federal Statistical Offices) β€” population, age, origin, housing
  • INKAR / BBSR β€” over 500 regional-statistics indicators at district level
  • destatis β€” e.g. insolvencies, tourism, vehicle stock
  • Federal Returning Officer β€” federal election results (most recently 2025)
  • KBA β€” Federal Motor Transport Authority (vehicle stock, EV share)
  • BKA PKS β€” police crime statistics
  • OpenStreetMap & BKG β€” geometries and accessibility

Source and data year appear in every fact-check. Nothing secret, nothing bought.

Check it yourself

This is the heart of it: you don't have to trust us. Every fact-check links the interactive map in the Atlas β€” the very dataset we used. A direct link opens exactly the indicator (or the combination of two indicators) the video was about.

We don't hide the counter-correlations either: if a different variable explains the pattern better, you can see that for yourself in the same map.

To the interactive map

Neutrality & corrections

Credibility is our most important asset. That's why, across a season, we deliberately mix confirmed and debunked claims from different directions β€” checking only one side isn't neutral.

We phrase things descriptively, not judgmentally, and name uncertainties openly. Spotted an error or a questionable call? Write to beratung@kaatai.de β€” we correct transparently and visibly.

As of 2026-06. This methodology grows with the data and the episodes β€” suggestions welcome.