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 Question from Kenneth: Hello: Does 0.01 represent both one percentage point and one percent in decimal form? What is, for example, 2/100 of one percentage point, and what is 2/100 of one percent? Are the answers the same. I thank you for your assistance.

Hi Kenneth,

0.01, $\frac{1}{100}$ and one percent are three ways of expressing the same quantity. One percent is 0.01.

A percentage point (pp) is the unit for the arithmetic difference of two percentages.

Consider the following hypothetical example: In 1980, 40 percent of the population smoked, and in 1990 only 30 percent smoked. We can thus say that from 1980 to 1990, the incidence of smoking decreased by 10 percentage points even though smoking did not decrease by 10 percent (actually it decreased by 25 percent) – percentages indicate ratios, not differences.

Penny

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