Percents in data are deceptively meaningless without good context. (Day 12, Fighting fake news)

A good habit is whenever you hear a percentage or “50 times greater” given, be skeptical. If the number sounds huge or fantastic, that should raise even more flags.

This is particularly important in our “fake news” world: recognizing likely false or misleading data isn’t easy, but is a trainable skill, and percents are very easy ways to spin data.

They’re always comparisons, so what number you’re comparing to matters a tremendous amount. “Grue-related deaths increased by 7000% this year”: did they go from 2->140, or from 10,000->700,000? Both are 7000%, but one is a concern and one is a health and safety nightmare that must be solved right now.

Is 20% a good success rate? If baseball batting average it’s bad, if it’s your annual likelihood of getting hit by a truck it’s awful. If it’s your out of hospital chance of surviving a heart attack you’re way ahead, and if it’s your chance of winning the Powerball this week you should actually buy a ticket. Context is everything!

A very important technical distinction: percentage point change vs percent change. Going from 20% voter participation to 30% is a *50%* increase, not 10%; it’s a 10 percentage point increase. Going from 70% to 80% is still 10 percentage points, but only a 14% increase. It’s absurd how often top tier, well edited media get this wrong, intentionally or otherwise.

I appreciate if this wasn’t the most exciting topic, but misrepresenting data is *how* bad news propagates, and technical knowledge is necessary to fight.

Getting good at recognizing quickly something that seems wrong, and digging/investigating a tiny bit before linking/sharing is a skill I know we can all get better at; and getting better at it will make the world a better place.

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