[ELI5] Why average of 12 months growth percentile is not the same as sum of growth percetnile?

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Jan 2022 sales 100
Jan 2021 sales 50

Feb 2022 sales 150
Feb 2021 sales 90

Jan sales growth is 100%
Feb sales growth is 67%
Average growth **83%**

2022 sales total 250
2021 sales total 140
Percent growth is **79%**

Why do i feel stupid, ama grown ass man and i cnt figure it out

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You might be talking about the Simpson’s Paradox – the average of some averages is not the average -> https://lemire.me/blog/2005/10/28/average-of-averages-is-not-the-average/

Aside from the answers that were already given, you’re probably looking for the term *percentages* rather than *percentiles*.

They’re very different things — percentiles are about ranking values on a cumulative scale of 100. For example, a student taking a math quiz can be said to have a 98th-percentile score when their score is higher than 98% of other scores they’re being compared with. The 50th percentile is also/better known as the median.

Hope this helps get you less confusing search results.

Average = SUM / COUNT.

That is, you add the items you want to average, then divide by the total number of items.

The average of 100 and 67 is 83.5, because that’s 167/2.

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Percent change is DIFFERENCE / ORIGINAL.

When they calculated the percent growth, they did 250-140 = 110, that’s the “difference” for the numerator.

The “original” number is 140, because 2021 is before 2022.

So we do 110/140 = 0.786