STAT231 Lecture 3: week 3-part 2.pdf
17 Jan 2014
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Summarization of data: algebraic approach. There are three aspects we look at. 1 n n i=1 xi n x_ x1 + x2 +xn. Central tendency: the mean: given a numerical data set. {x1,x2,x3,xn}, the arithmetic mean is given by. Other (rarely used) means: geometric mean. G. m = (x1* x2 *xn) 1/n: harmonic mean. Applications: (i) average interest rate (ii) average speed n. 1 x2: the median: this can be used when the data is ordinal. The mode is the one with the highest frequency. What about using the mean and median to summarize the old faithful geyser data? mean = 72. 31 median = 76. For the old faithful geyser data the value 78 appeared the most (16 times) so the mode is. For frequency or grouped data the group or class with the highest frequency is called the modal class. For the chlamydia data the modal class in both. Measures of dispersion: range = maximum minimum, quartiles:
