Percent vs percentage points
There are lies, damn lies and statistics. But the worst kinds of statistics are those that involve changing percentages.
When talking about increasing or decreasing numbers, almost everyone who stinks at math — myself included — routinely confuses “percent” with “percentage points.”
Let’s say that a classroom full of kids retakes a test, and the average score drops from 48.3 to 46.7. You could say, “The class’s average score fell 3.3 PERCENT.”
You could also say, “The class’s average score fell 1.6 PERCENTAGE POINTS, from 48.3 to 46.7.”
However, it would be incorrect to say, “The class’s average score fell 1.6 PERCENT, from 48.3 to 46.7.”
If you don’t like math, here is a website to determine percent change.
If all this is just too confusing, then simply do what I do — and don’t trust anyone who talks about changing percentages.