Lecture-2-Summer2010 - LECTURE 2 Descriptive Statistics:...

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LECTURE 2 Descriptive Statistics: Tabular and Graphical Methods This lecture covers material on frequency and relative frequency distributions, bar graphs, dot plots, histograms and cumulative distributions. Microsoft Excel is used for some applications. Read: Chapter 2, Sections 2.1, 2.2. Frequency Distributions: A frequency distribution is a tabular summary of data showing the frequency of items in each of several non-overlapping classes. For qualitative data, as shown in Tables 2.1 and 2.2, each class is defined by the name or label (in this case names of soft drinks). For quantitative data, defining non-overlapping classes requires three steps (as shown in pp. 34- 35): 1. Select the number of classes. Note: A rule of thumb in determining the number of classes is to take the square root of the sample size (i.e., number of observations in the sample or n ), and round it upwards to the nearest integer. Example: If the number of observations or n = 20, then square root of 20 = 4.47. Rounding upwards to the next integer, number of classes = 5. 2. Determine width of each class. 3. Determine the class limits. 1
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EXAMPLE 2.1 A credit card company takes a random sample of monthly payments that it receives. The sample size
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This note was uploaded on 09/21/2011 for the course OM 210 taught by Professor Singer during the Summer '08 term at George Mason.

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Lecture-2-Summer2010 - LECTURE 2 Descriptive Statistics:...

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