POLSCI 3NN3 Lecture 6: LEC 6 - JAN 23 - VARIANCE
28 Jan 2017
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Some measures of dispersion are more appropriate for certain levels of measurement (variables: variation ratio is a quick and easy - for nominal, more options for other levels. Measures the average squared distance of scores away from the mean. Data (xi scores): | 2 | 5 | 6 | 8 | 9 | Step one: (finding how far away these scores far away from all scores) Step three - what is the average distance (do an average of the deviation: (-4)+(-1)+(0)+(2)+(3)=0, 0/0=0. Therefore, average distance away from average is 0 (will always happen: cannot do this. Square values takes away negative numbers: getting rid of negatives allows you to come up with a number that can then be divided by number of cases. Step two- find out how far each case is away from average: =(cid:2871)05, =6, = distance from average. Step two (for real) - find out how far each case is away from average + square it.
