1. Chapter 11 Where Do Data Come From?

2. Statistics: Concepts and Controversies

3. Chapter 13 What is STATISTICS ? Using ‘data’ to draw a conclusion about something unknown. Decision making in the presence of uncertainty.

4. Chapter 14 What Is “Data”? (better: What are data?) Pieces of information. Numbers. The above are data only if the information has a meaning attached.

5. Chapter 15 How Data are Obtained Observational Study – Observes individuals and measures variables of interest but does not attempt to influence the responses – Describes some group or situation – Sample Surveys are a type of observational study Experiment – Deliberately imposes some treatment on individuals in order to observe their responses – Studies whether the treatment causes change in the response.

6. Chapter 16 Common Language Individuals Population – entire group of individuals about which we want information Sampling Frame – individuals that could possibly be selected for the sample (not necessarily the same as the population) Sample – subset of individuals from which information is collected Sample Survey – type of observational study; data collected on a sample Census Variable – characteristic of an individual

7. Chapter 17 Population individuals

8. Chapter 18 Sampling Frame 1 9 2 345 6 7 8 10 17 16 15 13 14 12 11 List of Individuals 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Sample

9. Chapter 19 Sample Survey measurements data

10. Chapter 110 List of Individuals 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Census 1 9 2 345 6 7 8 10 17 16 15 13 14 12 11 1 9 2 345 6 7 8 10 17 16 15 13 14 12 11 Census

11. Chapter 111 Case Study The Effect of Hypnosis on the Immune System reported in Science News, Sept. 4, 1993, p. 153

12. Chapter 112 Case Study The Effect of Hypnosis on the Immune System Objective: To determine if hypnosis strengthens the disease-fighting capacity of immune cells.

13. Chapter 113 Case Study 65 college students. – 33 easily hypnotized – 32 not easily hypnotized white blood cell counts measured all students viewed a brief video about the immune system.

14. Chapter 114 Case Study Students randomly assigned to one of three conditions – subjects hypnotized, given mental exercise – subjects relaxed in sensory deprivation tank – control group (no treatment)

15. Chapter 115 Case Study white blood cell counts re-measured after one week the two white blood cell counts are compared for each group results – hypnotized group showed larger jump in white blood cells – “easily hypnotized” group showed largest immune enhancement

16. Chapter 116 Case Study The Effect of Hypnosis on the Immune System What is the population? What is the sample?

17. Chapter 117 Case Study The Effect of Hypnosis on the Immune System What data were collected? Easy or difficult to achieve hypnotic trance Group assignment Pre-study white blood cell count Post-study white blood cell count

18. Chapter 118 Case Study The Effect of Hypnosis on the Immune System Is this an experiment or an observational study?

19. Chapter 119 Case Study The Effect of Hypnosis on the Immune System Does hypnosis and mental exercise affect the immune system?

20. Chapter 120 Case Study Weight Gain Spells Heart Risk for Women “Weight, weight change, and coronary heart disease in women.” W.C. Willett, et. al., vol. 273(6), Journal of the American Medical Association, Feb. 8, 1995. (Reported in Science News, Feb. 18, 1995, p. 108)

21. Chapter 121 Case Study Weight Gain Spells Heart Risk for Women Objective: To recommend a range of body mass index (a function of weight and height) in terms of coronary heart disease (CHD) risk in women.

22. Chapter 122 Case Study Study started in 1976 with 115,818 women aged 30 to 55 years and without a history of previous CHD. Each woman’s weight (body mass) was determined Each woman was asked her weight at age 18.

23. Chapter 123 Case Study The cohort of women were followed for 14 years. The number of CHD (fatal and nonfatal) cases were counted (1292 cases). Results were adjusted for other variables.

24. Chapter 124 Case Study Results: compare those who gained less than 11 pounds (from age 18 to current age) to the others. – 11 to 17 lbs: 25% more likely to develop heart disease – 17 to 24 lbs: 64% more likely – 24 to 44 lbs: 92% more likely – more than 44 lbs: 165% more likely

25. Chapter 125 Case Study Weight Gain Spells Heart Risk for Women What is the population? What is the sample?

26. Chapter 126 Case Study Weight Gain Spells Heart Risk for Women What data were collected? Age (in 1976) Weight in 1976 Weight at age 18 Incidence of coronary heart disease Other: smoking, family history, menopausal status, post-menopausal hormone use.

27. Chapter 127 Case Study Weight Gain Spells Heart Risk for Women Is this an experiment or an observational study?

28. Chapter 128 Case Study Weight Gain Spells Heart Risk for Women Does weight gain in women increase their risk for CHD?

29. Chapter 129 Key Concepts Knowing about statistical methods will have practical consequences in your every day lives. Experiment versus Observational Study Common Terms – Individuals, Population, Sampling Frame, Sample, Sample Survey, Census, Variable