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Unformatted text preview: PROBABILITY AND STATISTICS FREQUENCY DISTRIBUTION and MEASURES of CENTRAL TENDENCIES MATH 30: PROBABILITY AND STATISTICS Frequency distribution and Graphical Methods A frequency distribution is one of the most common ways to describe a single variable. Depending on the particular variable, all of the data values may be represented or you may group the values into categories. Frequency distributions can be depicted in two ways  either through a table or through a graph. Suppose we have the following test statistic from a group of 50 students. Construct a frequency table describing the said table. 88 62 63 88 65 85 83 76 72 63 60 46 85 71 67 75 78 87 70 43 63 90 63 60 73 55 62 62 83 79 78 43 51 56 80 90 47 48 54 77 86 55 76 52 76 43 52 72 43 60 Steps in Constructing a Frequency Distribution 1. Get the lowest and the highest value in the distribution. We shall mark the highest and lowest value in the distribution. 2. Get the value of the range. The range denoted by R, refers to the difference between the highest and the lowest value in the distribution. Thus, = 3. Determine the number of classes. In the determination of the number of classes, it should be noted that there is no standard method to follow. Generally, the number of classes must not be less than 5 and should not be more than 15. In some instances, however, the number of classes can be approximated by using the relation ? = + ?. ?? where ? = number of classes = sample size, and is the ceiling operator (meaning take the closest integer above the calculated value). Steps in Constructing a Frequency Distribution 4. Determine the size of the class interval. The value of C can be obtained by dividing the range by the desired number of classes....
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This note was uploaded on 08/30/2011 for the course COMPUTER computer taught by Professor Ms during the Spring '10 term at Oxford University.
 Spring '10
 MS

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