"Country A is top of Europe for X" makes a great headline. Before you believe it, ask four questions. They take a minute, and they catch most misleading comparisons.
1. Is everyone measuring the same thing?
Countries don't always define things the same way. What counts as a household, as working full time, or as leaving home can differ between national surveys. Bodies such as Eurostat publish harmonised figures, where every country follows a common definition, precisely so that comparisons are fair. Even then, there are footnotes: a country may have a break in its series, or a slightly different reference period.
That's why AboutAverage's European tables use harmonised Eurostat figures, show the year for each country, and carry any footnote that the source attaches.
2. Is it the same year?
Data arrives at different speeds. In any table, one country's latest figure may be from this year and another's from two years ago. We drop figures more than three years old, and show the year beside every value, so you are not comparing this year's country with an older snapshot without knowing it.
3. Is the gap bigger than the margin of error?
Many country figures come from surveys of a sample of households, not a count of everyone. Each carries a margin of error. When two countries are 0.2 points apart and each figure could be out by more than that, the order between them is close to a coin toss.
A made-up example: Country P reports 81.4% and Country Q 81.1%, each from a survey with a margin of error of about ±1 point. Ranking P above Q tells you very little. Ranking either above a country on 72% tells you a lot.
We say when a table is built from survey estimates. Treat neighbours in a table as roughly level, and look at the big gaps.
4. Is a ranking the right way to show it?
Ranks exaggerate small differences and hide big ones. Being 10th out of 27 sounds middling, but if the values are tightly bunched, 10th may be almost identical to 3rd. That's why our tables show the actual values, not just the positions, along with the EU figure for comparison.
Some comparisons we won't make
Where countries measure something too differently to compare honestly, we don't show a table at all. We also don't rank countries on sensitive topics such as religion or health. And we never combine averages from different countries into a new average of our own, because an average of averages ignores how many people each one describes.
League tables are fun, and they can be revealing. Read them as "roughly where countries stand on this definition, in these years", and they are a great way into how different, and how similar, life across Europe is.