Center of a data set: mean, median, mode  Measures of Central Tendency
Center of a data set: mean, median, mode
Lessons
Notes:
3 ways for describing the “center” of a data set:
1. mean ($\overline{x}$ or $\mu$): arithmetic average of a data set
$\overline{x}= \frac{x_1+x_2...+x_n}{n}$
$x$: data value
$n$: # of items in a data set
2. median: the “middle” of a sorted list of data values
3. mode: the data value that occurs most often in a data set
$\cdot$ The median is not affected by outliers, but the mean is.
$\cdot$ weighted mean($\overline{x}_{weighted}$): arithmetic average where some data values contribute more than others
$\overline{x}_{weighted}=$ $\frac{\sum_{{i=1}}^{n}x_i \cdot w_i}{\sum_{{i=1}}^{n}w_i}$

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