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Unformatted text preview: uely degined Robust MODE Categorical, Numerical No Yes MEDIAN Ordinal, Numerical Yes Yes MEAN Numerical Yes No Words that describe distributions
v༇ Unimodal : has one major peak
v༇ Bimodal: has two major peaks
v༇ Symmetric: there is a symmetry with respect to the middle point v༇ Skewed to the right: when the right tail (larger values) is much longer than the
left tail (smaller values) v༇ Skewed to the left Need a measure of spread
"GE" and "Philips" Lightbulb Lifetimes (in hours)
20 10 10 0 Frequency 20 0
500 600 700 800 GE 900 1000 540 620 700 780 860 940 Philips “GE” exhibits better quality control: not much variation.
“Philips” has more fluctuation although average is same as “GE”. MEAN and MEDIAN do not completely summarize a data set. Also need to know amount of gluctuation. SPREAD: Quartiles & IQR
v༇ Define first quartile to be the median of the observations
below the median.
v༇ Define third quartile to be the median of the observations
above the median. 1, 3, 3, 6, 8, 9
M=4.5
Q1=3
Q3=8 The interquartile range IQR is Q3  Q1 Example: customer satisfaction ratings
20 measurements on the 10 point scale: 9, 8, 3, 8, 10, 9, 8, 9, 5, 8, 1, 10, 8, 10, 7, 8, 9, 10, 5, 9 Quartiles? 1 3 5 5 7 8 8 8 8 8 8 9 9 9 9 9 10 10 10 10 Q1 = (7+8)/2 = 7.5 Md = (8+8)/2 = 8 Q3 = (9+9)/2 = 9 IQR = Q3  Q1 =...
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This note was uploaded on 01/15/2014 for the course BUAD 310 taught by Professor Lv during the Fall '07 term at USC.
 Fall '07
 Lv

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