3 Describing data

# 3 Describing data - Two common descriptions of data...

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Describing data Two common descriptions of data ! Location (or central tendency) ! Width (or spread) Measures of location Mean Median Mode Mean Y = Y i i = 1 n ! n n is the size of the sample !

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Mean Y 1 =56, Y 2 =72, Y 3 =18, Y 4 =42 = (56+72+18+42) / 4 = 47 Y Median ! The median is the middle measurement in a set of ordered data. The data: 18 28 24 25 36 14 34 can be put in order: 14 18 24 25 28 34 36 Median is 25. Mode The mode is the most frequent measurement.
The mean is the center of gravity; " the median is the middle measurement. " Mean and median for US household income, 2005 Median \$46,326 Mean \$63,344 Mode \$5000-\$9999 Why? "

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Mean 169.3 cm Median 170 cm Mode 165-170 cm University student heights " 150 160 170 180 190 200 210 0.2 0.4 0.6 0.8 1 Cumulative Frequency Height (in cm) of Bio300 Students Measures of width ! Range ! Standard deviation ! Variance ! Coefficient of variation Range 14 17 18 20 22 22 24 25 26 28 28 28 30 34 36 The range is the maximum minus the minimum: 36 -14 = 22
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3 Describing data - Two common descriptions of data...

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