## What's with the Greek? (4)

**The Greek lowercase letter for "M" (pictured above on the right) is pronounced as "mew."**

**This symbol represents the mean of a data set. **

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What's with the Greek?

**X Bar (pictured below under Sample Mean) is simply the mean of a given set of sample values. **

**As you will notice, "X Bar" is the same as the POPULATION MEAN, merely reexpressed. **

**Read **Sample Mean vs. Population Mean** for more information. **

** **

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What's with the Greek?

\[ \sigma \]

**This symbol, the lowercase "sigma," represents the **POPULATION STANDARD DEVIATION**. **

**The formula to calculate the population standard deviation is:**

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What's with the Greek?

**"SIGMA" means the SUM:**

**The "sum of what?" The sum of a set of values:**

EXAMPLE:

(1 + 2 + 3 + 4 + 5) = 15

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What's with the Greek?