1. wed, feb 4, 2015 using large data sets

2. Analyzing a research article Use the Analyzing Research Articles handout (need one?) Select one of the five research articles linked from our class schedule (listed under today’s readings Feb 4) Focus on the purpose of the study, description of study design (participants, methods, how they collected data), data analysis and conclusions Don’t worry about specific statistical analysis methods Due next Wednesday 2/11 – print or email to me by class time Format – whatever works for you (bullets, address some but not necessarily all questions/points from handout) Counts as one pop quiz (worth up to 2 points)

3. today’s line-up… Survey research as a method General Social Survey (dataset for our project) Project details, variables, think about groups SPSS & Virtual Lab

4. What is a survey? A survey is a: – systematic method for gathering information – from (a sample of) entities – for the purposes of constructing quantitative descriptors – of the attributes of the larger population of which the entities are members

5. Typically surveys: Gather information by asking people questions Collect information by either (1) interviewers asking questions and recording responses or (2) respondents reading and recording their own answers Collect information from a subset of the population, a sample, rather than from all members

6. The SAGE Handbook of Online Research Methods (2008) Based on probability design* *units are selected using a method that ensures that each unit has a known, nonzero probability of being included

7. 1936 election and the Literary Digest survey Magazine had predicted every election since 1916 Sent out 10 million surveys---and 2.4 million responded They said: Landon would win 57% of the vote What happened: 62% Roosevelt landslide

8. What went wrong? Sample not representative Lists came from subscriptions, phone directories, club members Phones were a luxury in 1936 Selection Bias toward the rich Voluntary response: Republicans were angry and more likely to respond Context: Great Depression – 9 million unemployed – Real income down 33% – Massive discontent, strike waves

9. Polls vs. Surveys No clear distinction between the two terms – “Poll” often used for private sector opinion studies Use many of the same design features as studies that would be called surveys – “Poll” rarely used to describe government or scientific surveys To me, the term poll implies either – A commercial or less-scientific study, or – A quick turn-around survey whose results may be of short- term interest

10. Steps in conducting a survey Clearly state research objective(s) Decide on survey mode(s) – How will you contact potential respondents? (web, email, phone, etc.) – In what media will the survey be given? (web, email, phone, etc.) Determine fielding strategy (how to maximize response rates?) Design the survey questions and the survey instrument

11. Determine sample size and sampling strategy Obtain Institutional Review Board (IRB) or other approval as necessary – Are respondents promised confidentiality? – What is the impact if their survey responses become known? Pre-test – Give the survey to some test subjects and get their feedback What works and what doesn’t? Are you getting correct data/information? – Revise and re-pre-test as necessary Steps in conducting a survey

14. General Social Survey The GSS (General Social Survey) is a biannual personal interview survey of U.S. households conducted by the National Opinion Research Center (NORC). The first survey took place in 1972. Approximately 3000 American adults are interviewed in person for about 90 minutes and asked around 450 questions.

15. http://www3.norc.org/gss+website/

16. Purpose of GSS gather data on contemporary American society in order to monitor and explain trends and constants in attitudes, behaviors, and attributes over time to compare the United States to other societies

17. General Social Survey demographics & attitudes – The questionnaire contains a standard core of demographic and attitudinal variables, plus certain topics of special interest selected for rotation (called "topical modules") – Items include national spending priorities, drinking behavior, marijuana use, crime and punishment, race relations, quality of life, confidence in institutions, and membership in voluntary associations

19. variables variable – a characteristic that can vary in value among subjects in a sample or a population. We are interested in similarities and differences - variance types of variables – categorical – quantitative

20. categorical variable scale for measurement is a set of categories examples: – Racial-ethnic group (white, black, Hispanic) – Political party identification (Dem., Repub., Indep.) – Vegetarian? (yes, no) – Mental health evaluation (well, mild symptom formation, moderate symptom formation, impaired) – Happiness (very happy, pretty happy, not too happy) – Religious affiliation – Major

21. SPANKING: Categorical (Single) Do you strongly agree, agree, disagree, or strongly disagree that it is sometimes necessary to discipline a child with a good, hard spanking? Categories: Code as: {strongly_agree} Strongly agree 5 {agree} Agree 4 {disagree} Disagree 3 {strongly_disagree} Strongly disagree 2 {dontknow} DON'T KNOW 1 {refused} REFUSED 0 Sample question from GSS

22. scales of measurement for categorical variables, two types:  nominal scale – unordered categories o preference for president, race, gender, religious affiliation, major opinion items (favor vs. oppose, yes vs. no)  ordinal scale – ordered categories o political ideology (very liberal, liberal, moderate, conservative, very conservative) o anxiety, stress, self esteem (high, medium, low) o mental impairment (none, mild, moderate, severe) o government spending on environment (up, same, down)

23. PRES12: Categorical (Single) Did you vote for Obama or Romney? Categories: Code as: Obama5 Romney4 Other Candidate (Specify)3 Didn’t vote for president2 Don’t know1 Refused0 nominal scale – unordered categories

24. POLVIEWS: Categorical (Single) We hear a lot of talk these days about liberals and conservatives. I'm going to show you a seven-point scale on which the political views that people might hold are arranged from extremely liberal--point 1—to extremely conservative--point 7. Where would you place yourself on this scale? Categories: Code as: Extremely liberal 7 Liberal 6 Slightly liberal 5 Moderate, middle of the road 4 Slightly conservative 3 Conservative 2 Extremely conservative 1 DON'T KNOW 0 REFUSED 8 ordinal scale – ordered categories

25. quantitative variable possible values differ in magnitude examples: – Age, height, weight, BMI = weight(kg)/[height(m)] 2 – Annual income – GPA – Time spent on Internet yesterday – Reaction time to a stimulus – (e.g., cell phone while driving in experiment) – Number of “life events” in past year

27. use of statistics to describe, summarize, and explain or make sense of a given set of data

28. Mean – Uses all of the data – Has desirable statistical properties – Affected by extreme high or low values (outliers - example) – May not best characterize skewed distributions Median – Not affected by outliers – May better characterize skewed distributions Comparison of mean and median UNC Geography Majors Salaries Example

29. mid-1980's at the University of North Carolina, the average starting salary of geography students was well over $100,000

30. CorrelationCausation

31. sample patterns from GSS data – median income of female respondents compared with average income of male respondents – median level of education of respondents who own a gun – number of female respondents who own a gun compared with number of male respondents who own a gun – average age of respondents who indicated the government should spend more on space exploration – self-reported level of happiness compared with income level

32. Sample characteristics of the GSS The sampling frame of the General Social Survey is all U.S. adults living in households. The sampling frame includes 97.3 % of all U.S. adults. Who does not live in a household? – college students in dorms – military personnel in barracks – prisoners – elderly persons in retirement homes

33. Does the GSS sample really draw from all the adults in its sample frame? After the GSS is sampled, only 70% of persons in the sample actually respond to the survey – 23% refuse or cut the survey off in the middle – 2% are unavailable or can’t be found – 5% are missing for other reasons In general, a response rate of 60% or more is considered minimally acceptable, but you should check your results in any way you can.

34. Let’s look at a GSS questionnaire Start at page 31

35. where can you access SPSS? Odum Institute – Davis Library 2 nd floor – ask lab assistant https://virtuallab.unc.edu Lab in the Undergraduate Library (need to confirm)

36. Notes… Bring a flash drive to the Odum lab on Monday – you may want to save your work Davis Library >> Room 219 The dataset that we are using (GSS 2012) is available for download on our class website – schedule>>feb 09 – the dataset is a.sav format – only opens with SPSS