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SP 225 Lecture 5. Percentages, Proportions, Rates of Change and Frequency Distributions. Proportion. The number of cases in one category of a variable divided by the number of cases in all categories of a variable. Rates. Definition: A proportion written with a base other than 1. Percentage.
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SP 225Lecture 5 Percentages, Proportions, Rates of Change and Frequency Distributions
Proportion • The number of cases in one category of a variable divided by the number of cases in all categories of a variable
Rates • Definition: A proportion written with a base other than 1
Percentage • Definition: a rate written with a base of 100
Percentage Change • Definition: A statistic that tells how much a variable has changed over time.
Frequency Distribution Definition: A table that summarizes the distribution of a variable by reporting the number of cases contained in each of its categories
Making Decisions Based on Ordinal Data • Cannot truly calculate an average score • Cannot directly compare categories
Frequency Tables for Interval/Ratio Data • Group categories • Groups represent ranges of values
Constructing a Frequency Table • Decide upon a number of groups • Find the range of data by subtracting the minimum value from the maximum value • Divide the range by the number of groups to get the minimum group size • Define the lower limit of the lower interval and begin building the groupings • Count the number of cases in each group
Example Frequency Table 5 10 17 13 8 12 19 22 15 3 9 2 14 16 20 19 18 7 14 23 14 21 28 18
Constructing a Frequency Table in SPSS • Use recode command to group data • Groups must be created manually before frequency table is constructed
Reading For Next Class • No Additional Reading