Getting proportions right.
WHAT A PERCENTAGE NEEDS
A base. Percentage of what.
WHAT GOES WRONG WITHOUT IT
Meaningless or misleading figures.
PERCENTAGE CHANGE AND PERCENTAGE POINTS
Different. A rate moving from ten to twelve percent is a two point rise and a twenty percent increase.
Confusing them misleads.
WHAT TO ALWAYS GIVE
The underlying numbers alongside the percentage.
WHAT TO BE CAREFUL WITH
Percentages of small bases Averaging percentages, which is usually wrong Compounding, where percentages apply successively
THE AVERAGING POINT
Averaging two conversion rates from different sized groups gives a wrong answer.
Recalculate from the totals instead.
WHAT TO CHECK
That the base is the same when comparing rates.
MARKUP AND MARGIN
Different, and the confusion costs money.
Fifty percent markup is thirty-three percent margin.
WHAT TO STATE CLEARLY
Which you mean, whenever you use either.
