ThinkCritical.eu · Manipulation atlas
Numbers and chartsPercentages without a base
“Up 100%” with no starting number – going from 3 to 6 cases is also 100%.
A percentage is always a share of something. Without the starting number you can't tell whether it's thousands of cases or three – and with small numbers, big percentages come very easily. Percentages and percentage points also get mixed up a lot.
A local newsletter reports: “Cellar break-ins up 200%!” Last year two were reported; this year six. Unpleasant, but it says nothing about a “crime wave”.
How to spot it
- A big percentage (“up 100%”, “tripled”) with no number it was calculated from.
- Strong words like “wave”, “explosion” or “record” for something that rarely happens anyway.
- Percentages and percentage points are mixed – “up 2%” is not the same as “up 2 percentage points”.
How to check and what to do
- Find the absolute numbers: from how many to how many. They are usually in the original source – police statistics, an official report or a press release.
- Compare with several previous years: are swings like this normal for such small numbers?
- Do the maths: if a rate rises from 4% to 5%, that's 1 percentage point – but a 25% increase.
Tip: With small numbers, big percentages are almost guaranteed. Only the absolute numbers show whether there's reason to worry.
Full explanation and exercises:
thinkcritical.eu/en/manipulation-atlas/missing-base