Stat_Chapter 3 Key Words

2 heights of the players vary from the mean of 75

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Unformatted text preview: ample standard deviation s= ∑ ( ̅) = 156/4= 6.2 Heights of the players vary from the mean of 75 inches by 6.2 inches Variation and Standard Deviation – the more variation there is in a data set, the larger is the standard deviation Computing Formula for a Sample Standard Deviation (alternative formula) = ∑ ∑ ⁄ = Three Standard Deviations Rule – almost all the observations of any data set lie within three standard deviations to either side of the mean 3 Chebychev’s rule – 89% lie within three standard deviations on either side of the mean Empirical Rule – if distribution of the data set is bell shaped, then 99.7% of the observations lie within three standard deviations to either side of the mean. 3.3 The Five-Number Summary: Quartiles and Boxplots (invented by Tukey) Percentiles – divide data set into hundreths Deciles – divide data set into tenths Quintiles - divide data set into fifths Quartiles – divide the data into fourths = First Quartile Q1, = 25 median below the actual data median; Second Q2, = middle, median; Third 50% Q3 = 75% median above the actual data median, Q4 = 100% Quartiles for Distributions: Uniform; Bell Shaped; Right Skewed (tail to right); Left...
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