Where percentage change shows up in real life
Percentage change is one of the most common mental models in money, analytics, school, and everyday shopping. It shows up in salary raises, price changes, margins, conversion rates, and year-over-year comparisons.
Why the starting value matters
The exact same absolute change can imply very different percentage moves depending on the original base. A $20 change on $80 is a much bigger relative move than a $20 change on $800.
Common mistakes
- Mixing up percentage change and percentage points.
- Using the ending value as the base instead of the starting value.
- Assuming equal drops and gains cancel out automatically.