Statistics

1. Statistics Yikes!

2. Why do we use statistics • Summarize large numbers of responses • Remember the focus group? • To make comparisons • Do men like RC better, or do women? • To examine relationships • Are greater amounts of advertising associated with higher sales?

3. Statistics that help to summarize • Frequencies • Measures of central tendency • Mode • Median • Mean

4. Mode • The most frequently occurring response • What is the mode for this sample? • Male, Male, Female, Male, Female, Male • How about this sample? • A, B+, A, C, D • And this one? • 100, 98, 94, 94, 88, 86, 86, 84, 80

5. Mode • Mode=Male • Male, Male, Female, Male, Female, Male • Mode=A • A, B+, A, C, D • Mode=94 and 86 • 100, 98, 94, 94, 88, 86, 86, 84, 80 • What levels of measurement are these scales?

6. Mode • Strengths: • Can be used with any level of measurement • Easy to calculate and understand • Bad points: • Can be wildly inaccurate as an “average” • There can be many modes, or none at all.

7. Median • The point on a measure where half of the responses are above and half are below. • Requires that observations can be ranked Sample A C+ B- D B Sample (ranked) A B The median B- C+ D

8. Median • Which observation is the middle one? • If you have an odd number of observations (n), then the middle observation (after ranking) is (n+1)/2. • Odd # 1, 4, 6 • Observe n = 3. (3+1)/2 = 4/2 = 2 = 2nd observation • 4 is the second observation • Median = 4

9. Median • Which observation is the middle one? • # observations is even, then you average the two middle observations: (n/2) and (n/2)+1 • 2, 4, 6, 8 • (n/2) = (4/2) = 2 = second observation • (n/2) + 1 = 2+1 = 3 = third observation • Average of 4 (2nd obs) and 6 (third obs) is 5 • Median is 5

10. Median • Good points • Usable with any level of measurement except nominal • Much better “average” than mode • Good and bad point: • Not sensitive to extremes or to size of scale intervals Sample 1: 1, 2, 4, 7, 10 Sample 2: 1, 2, 4, 7, 10 million

11. Mean • Most common measure of “average” • Usable only with interval or ratio measures • To get a mean: sum the observations, then divide by the number of observations (n). • Obs: 2,4,3,1,8,0 Sum: 2+4+3+1+8+0=18 • Divide by n n=6 18/6= 3 The median? • 2.5

12. Mean • Good Points: • Commonly used and understood • Sensitive to scale intervals • Bad Points: • Cannot be used with nominal or ordinal data • Can be distorted by extreme observations

13. Getting information from surveys • SPSS is a statistical program • Excel on steroids • Set up like a spreadsheet

14. An example of data analysis

15. Frequencies printout in SPSS How interested are you in participating in a study abroad program while at UF? Frequency of occurrence Percent of occurrence Values

16. Frequencies printout in SPSS How interested are you in participating in a study abroad program while at UF? Percentages w/o missing values Sums the percentages

17. Frequencies printout in SPSS How interested are you in participating in a study abroad program while at UF?

18. Frequencies printout in SPSS How interested are you in participating in a study abroad program while at UF?

19. How do we use this output?

20. How do we use this output? • Use frequencies to get a mean for each dimension: • Low price: M = 4.67 • Safety: M = 3.92 • Fuel efficiency: M = 2.91 • Reliability M = 4.85

21. How do we use this output? Problems with the output?

22. How do we use this output? Figure 1: Average importance ratings for car attributes Scale: 1=Not important, 5=Very important

23. Answering objective 1 • Fact: • Car buyers are most interested in reliability and low price • Implication: • Jetta is well-positioned to compete on reliability. The target audience should be given facts to support this: our warranty, our JD Power reliability award, our excellent review from Consumer Reports, etc. • Although the Jetta is not a low price car, it is average for its class

24. Answering objectives 1,2, & 3 • Can be done using the frequencies command if you request item means • Note: you do not need to report the actual frequencies in the report, just the appendix

25. What do you do in your report • Title page, • Exec Summ, • Intro (Objectives+method) • Body (Subheads organized by objectives) • What you found (describe statistically) • What it means (your analysis) • Overall conclusions • Printouts in appendix

26. The body • Report on the data analysis • Use statistics and graphs to answer the objectives for the paper

27. Figure 1: Preferred Cola Coke Pepsi RC Percent responses to “My preferred brand of colas is:”

28. Figure 2: Cola preference by Gender Percent within each gender group responding to “My preferred brand of colas is:”

29. Implications • Our data suggest two important themes: first, Coke is the brand preferred most overall, second, men show a greater preference for Coke than do women. • In our view, this reinforces the need to more aggressively position Coke as a beverage for women cola drinkers.

30. Your implications • Be helpful to the creative • Remember, you are developing an advertising solution, not a marketing solution.