STAT1051_lesson3-2

# STAT1051_lesson3-2 - with its height proportional to the...

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1 Frequency Distribution Dataset is summarized in a tabular form. Range of the dataset is partitioned into a number of classes of equal width. Frequency distribution table is constructed by counting number of observations (called frequency) in each class and presenting the classes and their frequencies in a tabular form.

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2 Guidelines Guidelines for selecting number of classes: Use between 5 and 20 classes. Larger datasets require a larger number of classes. Smaller data sets usually require fewer classes Guidelines for deciding class-width: Use classes of equal width. Adjacent Class Width Classes of Number Obs. Smallest Obs. Largest -
3 Histogram A common graphical presentation of frequency distribution is a HISTOGRAM. The variable is placed on the horizontal axis and the (relative) / frequency is placed on the vertical axis. A rectangle is drawn above each class interval

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Unformatted text preview: with its height proportional to the frequency of that class. Rectangles are adjacent. 4 Graphical Summary Using SPSS SPSS can be used to get the histogram as well. Look at the beanie dataset. Consider a typical dataset. There are four variables. Name, Age, Value and Status (retired or not). We want to construct histogram for the a) Age variable b) Value variable. 5 SPSS window 6 Histogram Using SPSS AGE Histogram Std. Dev = 15.92 Mean = 26.5 N = 50.00 60.0 50.0 40.0 30.0 20.0 10.0 16 14 12 10 8 6 4 2 0 7 Variable: Value VALUE Std. Dev = 313.16 Mean = 128.9 N = 50.00 2000.0 1600.0 1200.0 800.0 400.0 0.0 50 40 30 20 10 8 Sample Size and Histogram Number of Observations in Data Set Number of Classes Less than 25 5-6 between 25-50 6-10 More than 50 10-20...
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## This note was uploaded on 11/27/2011 for the course STAT 1051-10 taught by Professor Balaji during the Fall '11 term at GWU.

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STAT1051_lesson3-2 - with its height proportional to the...

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