Stretch: Center, Spread, and Outliers
I can choose a measure of center or spread that fits the shape and context of the data.
🧠 The Challenge
meanmedianoutliercenterspreadrange
Pick the measure that fits the data. With a strong outlier or skew, the median describes the center better than the mean. For symmetric data with no outliers, the mean works well. To show spread, use the range or IQR.
👀 Worked Example
Incomes {20, 22, 25, 21, 300}: the 300 is an outlier, so the median (22) describes the center better than the mean (77.6).
✏️ Your Turn
0 of 3 checks complete
1. A data set has one very large outlier. Best measure of center?
2. Data is symmetric with no outliers. A good center measure is…
3. Which measure describes the SPREAD of the data?
💬 Explain Your Thinking
Explain why the median can be better than the mean when there is an outlier:
"An outlier is a value that is very blank. It pulls the blank toward it, so the blank better describes the center."