Lesson 2.pdf - Lesson 2 Numerical Descriptive Statistics...

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Lesson 2: Numerical Descriptive Statistics Graphical methods provide good visual summarization to the data. Sometimes just a visual impression of the data is not enough. Here, our goal is to summarize the data by giving numerical measures of center and spread in addition to a verbal description of the data. Measuring Center Mean (average: ࠵? ) To find the mean of a set of observations, add their values and divide by the number of observations. Example : Number of hot dogs eaten by contestants 7 40 42 51 52 60 62 67 68 68 70 70 73 76 77 78 81 81 82 95 95 96 97 a. Find the mean of the above data b. Suppose that the outlier 7 was a mistake happened when recording the data. It really was 70. Now the mean is
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Median (m) Median is the midpoint of the data. To find the median Example : For the hot dog data Now change 7 to 70 and re-calculate the median. Comparing Mean and Median
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Mean and Median of Skewed Distributions Symmetric Right-Skewed Left-skewed Measuring Spread Inter quartile range (IQR)
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