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Review Sheet
Mean
: average = Sum/n
median
:middle of series
mode
: most common
Outliers
: far removed from the rest of the data
Variability:
Minimum:
smallest number
maximum
: largest number
range:
distance between minimum and maximum
⁃
interquartile range: differences between the upper and
lower quartiles
⁃
Quartiles are the medians of the two halves of the list
⁃
lower quartile: one quarter from the bottom
⁃
upper quartile: one quarter from the top
How to read stem and leaf plots:
How to read histogram
s: display the shape of date distributions
1. Divide dataset into intervals, or bins, or equal width
2. Count # of cases per bin
3. Bar height = # of cases within that bin
Shapes:
can be derived from a certain kind of picture of the data
bell
: symmetric and shaped like a bell
symmetric
: one that you can split in half evenly
skewed:
Negative (left) skew: tail goes down toward
negative numbers
Positive (right) skew: tail goes toward positive
numbers
Standard deviation
: a measure of the spread of a distribution of
numbers. It is the average distance from the mean
•
Calculate the mean
•
find deviations from the mean for each value(valuemean)
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Square these deviations
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 Fall '07
 Lillie

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