Statistical Sciences 1024A/B Lecture Notes - Lecture 2: Interquartile Range, Quartile, Standard Deviation
30 Sep 2015
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Describing distributions with #s: focus on measures of centre & spread & choosing. Measures of centre & spread are best: measures of center. Other (not in text);midrange/midpoint, mode: measures of spread. Ss1024a ch 2 lecture notes (w2013: measures of center, mean. For n cases, x1,x2,x3, xn the mean is x , where x = (sum of values)/(count of values) Golf scores example (will refer to throughout this note): 10 golf scores; 90 87 95 86 81 102 105 83 88 79. A measure is resistant if its value changes only slightly to changes in a few observations, no matter how large those changes are. Golf example: replaced 4th observation score of 86 with 126: median. Middle value(when values are ordered) , i. e. half the values are above, half the values are below. Median is considered a resistant measure (golf example) Ss1024a ch 2 lecture notes (w2013: median(continued) For n odd, median is the middle observation.
