9. Measures of Center, Spread, and Position
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To start, press the STATbutton. Choose EDIT to enter the data and once it is done, press the STAT button again and choose CALC to find the one-variable statistics.
To find the lower and upper quartiles, you need to scroll down to the second screen. Lower Quartile: Q_1= 16.1 Upper Quartile: Q_3= 16.6 The interquartile range is the difference of the upper and lower quartiles. Interquartile Range: IQR= 16.6- 16.1= 0.5 The next step is to find the values beyond which any outliers would lie. To get these values we subtract 1.5 times the interquartile range from the lower quartile and add the interquartile range to the upper quartile. Q_1-1.5* IQR= 16.1-1.5( 0.5)=15.35 Q_3+1.5* IQR= 16.6+1.5( 0.5)=17.35 An outlier is a value either less than 15.35 or greater than 17.35. 16.7,16.8,15.9,16.1,16.5,16.6,16.5,15.9,16.7,16.5 16.6,14.9,16.5,16.1,15.8,16.7,16.2,16.5,16.4,16.6 There is one such value, 14.9. It is the only outlier.
16.7,16.8,15.9,16.1,16.5,16.6,16.5,15.9,16.7,16.5
16.6,17.35,16.5,16.1,15.8,16.7,16.2,16.5,16.4,16.6