| 2.1 | Centers of Data |
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- The median, or median value, is a value such that just as many data points are greater than that value as are less than it.
- If the number of data in the set is even, we take as the median the average of the two middle values.
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| Example |
- To find the median of a set of values, first arrange them from high to low (or low to high, as is done in a line plot).
- If there are an odd number of data, find the value such that just as many data are above it as below it.
- If there are an even number of data, find the average of the middle two values.
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 Experiment
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- It sometimes happens that a data set has concentrations of values away from its center; For example:
- There are two clumps in these data. One concentration of temperatures is roughly in the range from 10 to 20 degrees below zero. The other group is above 40 degrees. The median here is +15.5, showing us that very few data appear near the center of this data set.;
- If a set of data has two areas of high concentration, it is called bimodal.
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