week2 - 3 Empirical Rule If the distribution of the data is...

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1 Statistics 511 Descriptive Statistics Relevant Sections: 3.3 – 3.7 Numerical Descriptive Statistics A. Measures of Central Tendency 1. Mean (average) 2. Median a. If n (sample size) is odd: b. If n is even: 3. Mode Example (patients’ ages): 62, 81, 63, 73, 81 Mean Median Mode Comparing Mean and Median 1. Extreme values 2. Distribution shape a. Symmetric b. Skewed to left (negatively skewed) c. Skewed to right (positively skewed)
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2 B. Measures of Variability 1. range 2. (pth) percentile Special case: quartile 3. interquartile range (IQR) 4. variance 5. standard deviation Example (patients’ ages): 62, 81, 63, 73, 81 Find the range, IQR, variance and standard deviation
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Unformatted text preview: 3 Empirical Rule If the distribution of the data is approximately bell-shaped: Application of Empirical Rule Graphical Descriptive Statistics Frequency Relative frequency 1. Histograms 2. Stem-and-Leaf Plot Example: For both histograms and stem-and-leaf plots, we can look at general shape of distribution: a. Symmetric b. Skewed to left (negatively skewed) c. Skewed to right (positively skewed) 4 3. Boxplots Side-by-side boxplots Distribution Shapes a. Symmetric b. Skewed to left (negatively skewed) c. Skewed to right (positively skewed) 4. Scatterplot...
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This note was uploaded on 04/28/2008 for the course ST 511 taught by Professor Prof.kimweems during the Spring '08 term at N.C. State.

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week2 - 3 Empirical Rule If the distribution of the data is...

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