What everyone should know about "percentages"

I admit I’m a data freak. I loves me some good stats. But one has to be very careful when interpreting data, especially something like “percentage increase.”

For example, in this article, the sub-head states: “Millennials show the highest increase in participation [of loyalty programs]”

The article goes on to say “… participation jumped 19 percent year-over-year, with the most significant increase exhibited by Millennials (people between 18 and 25 years of age), among whom the level of participation spiked by nearly 32 percent.”

But when the whole number is so small (or conversely, so large) to start with, this may be meaningless data. As you can see in the article, “Affluents” participate at a nearly 80% level in 2007. So even if 100%!!! of affluents participated, that would only be a 20% increase.

On the flipside, Gen Y is participating at less than 50% in 2007, so if they were to go to 100% participation, that would be a 100% increase.

When the bases are different, the percent increase can be misleading. So be very careful when you hear things like “our membership increased 25%” or “our event registration increased by 10%.” Without knowing the base number, the percentage increase or decrease may be meaningless.

About Wes Trochlil

For over 30 years, Wes has worked in and with dozens of associations and membership organizations throughout the US, ranging in size from zero staff (all-volunteer) to over 700. In that time Wes has provided a range of consulting services, from general consulting on data management issues to full-scale, association-wide selection and implementation of association management systems.

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