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Data Summaries. Summary Statistics Given a large set of numbers, we often want to describe, or summarize, the data with a few revealing numbers. Example:

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Presentation on theme: "Data Summaries. Summary Statistics Given a large set of numbers, we often want to describe, or summarize, the data with a few revealing numbers. Example:"— Presentation transcript:

1 Data Summaries

2 Summary Statistics Given a large set of numbers, we often want to describe, or summarize, the data with a few revealing numbers. Example: Yearly sales of two brands of peanut butter

3 Summary Statistics Given a large set of numbers, we often want to describe, or summarize, the data with a few revealing numbers. Example: Yearly sales of two brands of peanut butter

4 Summary Statistics Example: Yearly sales of two brands of peanut butter Measurements of Center Arithmetic Mean: The Average Median: The data point in the center

5 Summary Statistics Example: Yearly sales of two brands of peanut butter Skippy Mean: Jif Mean:

6 Summary Statistics Example: Yearly sales of two brands of peanut butter Median: Order the Data If even number average the two center numbers If odd number report the center number

7 Summary Statistics Example: Yearly sales of two brands of peanut butter Median: Order the Data If even number average the two center numbers If odd number report the center number two center numbers Skippy and Jif Median = 11

8 Why Use A Median? Example: Sales Force Compensation

9 Why Use A Median? Example: Sales Force Compensation

10 Why Use A Median? Example: Sales Force Compensation

11 Why Use A Median? Example: Sales Force Compensation

12 Summary Statistics Measurements of Variation Range: Largest - Smallest Standard Deviation: Square Root of Variance Variance: Average Squared Difference

13 Summary Statistics Example: Yearly sales of two brands of peanut butter Range: Largest - Smallest Skippy: Jif:

14 Summary Statistics Example: Yearly sales of two brands of peanut butter Variance: Average Squared Difference: Skippy Only

15 Summary Statistics Example: Yearly sales of two brands of peanut butter Variance: Average Squared Difference: Skippy Only

16 Summary Statistics Example: Yearly sales of two brands of peanut butter Variance: Average Squared Difference: Skippy Only

17 Summary Statistics Example: Yearly sales of two brands of peanut butter Standard Deviation: Square Root of Variance Skippy: Jif:

18 Graphical Summary A Picture is Worth a Thousand Words (Bar Chart)

19 Summary Statistics A Year Worth of Weekly Sales Figures

20 Summary Statistics Summary Statistics: Using SPSS Skippy Range = = Jif Range = = 5.01

21 Graphical Summary Bar Chart

22 Graphical Summary Line Chart

23 Graphical Summary Histogram

24 Graphical Summary The Box and Whisker Plot

25 Antidepressant Survey Questionnaire Administered to 178 Physicians Randomly Selected from 100,000 physicians who prescribe of antidepressant drugs Investigating Physician Usage of Antidepressant medication

26 Questionnaire

27 Questionnaire

28 Summary Statistics Frequency Data (0/1 or 1 From Many)

29 Graphical Summary Pie Chart

30 Prescription Rates

31

32 Prozac Rates by Physician Type First, Box Plot Summaries by Physician Type Second, ReCode Data - High/Average /Low Prescription Rates

33 Prozac Rates by Physician Type Box Plot Summaries by Physician Type

34 Prozac Rates by Physician Type ReCode Data –Low Rate = 0 to 10 prescriptions per month –Average Rate = 10 to 20 prescriptions per month –High Rate = 20+ prescriptions per month

35 Cross Tabulating Data Create a Table Which Summarizes Number in Each Level

36 Graphing the Cross Tabulation Same Information Can be Summarized Using a Bar Plot

37 Next Class Period in Computer Lab Don’t forget: Next Period 11&14 BAB – from 7:15 p.m. to 9:00 p.m. We will not meet during the regularly class time during the day. Also, please bring a floppy disk to class, to save your work.


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