STAT 201 Chapter 2.4: Book Notes Chapter 2.4
19 Sep 2016
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Range is simple to compute and easy to understand, but uses only extreme values and ignores other values. Not resistant and ignores numerical values of nearly all data. Deviation gives a summary of variability by using all of the data. Describes a typical distance of how far data falls from the mean. Deviation= the difference between the observation and the sample mean o. Deviation is positive when an observation falls above the mean: negative when observation falls below the mean. Variance= the average of the squared deviations: its square root is called standard deviation. Symbol is called sum of squares: represents finding the deviation for each observation, squaring each deviation, and then adding them. The larger the standard deviation, the greater the variability of the data. S=0 only when all observations take the same value: ex. If reported ideal number of children for seven people is 2, 2, 2, 2, 2, 2,
