Announcements

1. Announcements • Thursday, Survey Analysis II due • Tuesday, November 25, Lab day in 250 • Saturday, December 13, 3:00-5:00 • Survey Research, Chapters 9,10,11,12,13 • Statistical Analysis, Chapters 16,17, &18

2. Items and Scales Measurement Part 2

3. Levels of Measurement • Nominal coded data: Ability to distinctly categorize, or conversely, allows the determination of equality. • Ordinal coded data: Allows determination of magnitude, rank, greater or less than. • Interval coded data: Captures the distance apart two or more respondents are with respect to an attribute. • Ratio data possess a natural or absolute zero, indicating a true absence of a characteristic. Permits statements concerning the equality of ratios.

4. Objectives • Characteristics of questionnaire items • Distinguish between single-item measures versus composite scales, “batteries of items.” • Qualities of measurements • Validity • Sensitivity • Reliability and error • Examples of scales used in marketing research

6. Clarifications • The term questionnaire item is used to denote a single question on a survey, corresponding to a single column in a dataset. • Scales typically denote sets of questions which become mathematical combinations of survey items.

7. Scaled-Response Format Questions • Labeled: All positions, especially mid-point and intermediate positions for the respondent are marked, or bear “labels” • Unlabeled: No intermediate points are labeled, sometimes positions bear only numbers.

8. Likert item:LabeledPeople should shop at local merchants even though the prices may be significantly higher. 1 . . . . . . 2 . . . . . . 3 . . . . . . 4 . . . . . . 5 Strongly agree Strongly disagree Disagree Neutral Agree Numeric differential item: Unlabeled Paying higher prices at local merchants... Shows intelligence Shows ignorance 1 . . . . 2 . . . . 3 . . . . 4 . . . . 5

9. Adding too many labels • 1 . . . . 2 . . . . 3 . . . . 4 . . . . 5 . . . . 6 . . . . 7 Agree somewhat Strongly agree Strongly disagree Disagreesomewhat Disagree Neutral Agree • 1 . . . . 2 . . . . 3 . . . . 4 . . . . 5 . . . . 6 . . . . 7 Never Rarely Seldom Irregularly Often Regularly Always

10. Single-items adequate for measurement? • Suppose an instructor had single-question exams? • Suppose the ACT (or GMAT) had only 5 possible scores (similar to A,B,C,D,F grades)? • Suppose the ACT had only 4 questions, 1 each for mathematics, English, reading comprehension, and science? These are the issues behind marketing research use of multiple-item scales.

11. Composite, or Multiple-Item Scales • Capture the sensitivity to the continuous nature of many subtle differences in between consumers. • Simultaneously address concerns of: • Accuracy: Just as a 25-question exam can ask questions evaluating the many topics covered in a course, multiple-item scale can ask the many subtle aspects that underlie a consumer attitude or behavior. • Consistency: Though we do not administer the same surveys repeatedly to the same consumers, we strive to develop scales that consumers would provide consistent responses to over time. • All relate to larger issue of measurement error.

12. Semantic Differential Scale Indicate your impression of shopping at Dillard’s by checking the box corresponding to your opinion for each pair of descriptions. Good value Unfamiliar brands Distinctive fashion Low quality Helpful staff Poor value Best brands No fashion High quality No staff

13. Brand Personality: CompetenceHow do the following terms describe your view of the Cingular brand? Reliable Secure Intelligent Successful Technical Confident Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive

14. Brand Personality: ExcitementHow do the following terms describe your view of the Cingular brand? Trendy Exciting Imaginative Up-to-date Cool Contemporary Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive Not at all descriptive __:__:__:__:__Extremely descriptive

15. VALIDITY AND RELIABILITY OF MEASUREMENTS • Validity: Accuracy • Conceptual Issue • Face Validity • Predictive Validity • Reliability: Consistency • Proportion of statistical error • Test-Retest • Inter-Item Correlation • Increasing the number of questions (items) can increase both the validity and reliability of a scale.

16. “I have bought “Joy” every time I have purchased dishwashing liquid in the last two years. • “I will buy “Joy” whenever I receive a cents-off coupon. • “I really notice the television ads for “Joy” dishwashing liquid. • “I have a bottle of “Joy” in my kitchen cabinet. • “I plan to purchase “Joy” on my next trip to the grocery store.”

17. SCALED-RESPONSE QUESTION FORMATS • Modified Likert • Semantic Differential • Numeric Differential • Composite Scales • Formative Composite Scale • Reflective Composite Scale

18. Formative Scale Items: Satisfaction • “My last flight on TWA departed on-time. • “TWA did not lose my luggage on my last trip. • “TWA has competitive fares.” • “TWA ticketing personnel are polite. • “TWA has friendly reservation operators. • “TWA has ample leg-room for me in coach seating. • “I have not been “bumped” from a TWA flight in the last two years.”

19. Additional items related to satisfaction • “I know it’s not the airline’s fault when a flight is cancelled. • “It upsets me to know others on the same flight have paid a lower price for their seat. • “An airline could always be on-time if they made that their priority. • “The two-item restriction on carry-on luggage is insensitive to the needs of today’s passengers.”

20. Reflective Items: Materialism • “I admire people who own expensive homes, cars, and clothes. • “Some of the most important achievements in life include acquiring material possessions. • “I don’t place much emphasis on the amount of material objects people own as a sign of success.* • The things I own say a lot about how well I’m doing in life. • I don’t pay much attention to the material objects other people own.* * Reverse coded

21. Please check the items in your kitchen: • Electric frying pan • Food processor • Spring-form pan • 9” cake pan • Flour sifter • Hand-held electric mixer • 10” frying pan • 2-quart sauce pan • Rotary blender • Pressure cooker • Cookie sheet • Cake icing spatula

22. Formative and Reflective Items • Formative items: Can be combined to measure the multiple aspects of a construct, though not necessary that respondents answer each item similarly. • Reflective items: Measures a single trait and respondents should answer each item similarly.

23. Correlation Coefficient • rxy, “the correlation between x and y” • The denominator is always positive. • The numerator will be negative when… • The numerator will be positive when…

24. Percent Shared Variance • If two “reflective” items correlation (rxy) is squared, the correlation ranges from 0 to 1.00 (instead of -1.00 to +1.00). • This squared correlation (rxy2) is equivalent to a percentage of shared variance. • If the two items are asking about a common subject, this is viewed as the degree they measure the same “trait.”

25. Example: Farm Credit Survey

26. “Percent” shared variance • Correlations, .669, .718, .764 • Squaring the correlations: .448; .516; .583 or 44.8%; 51.6%; 58.3% shared variance in pairwise combinations of items.

27. Cronbach’s Alpha for k items