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Chapter 1Thought Question 1Thought Question 2Thought Question 3What is STATISTICS ?What Is “Data”? (better: What are data?)How Data are ObtainedCommon LanguagePopulationSampling FrameSample SurveyCensusCase StudySlide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Key ConceptsChapter 1 1Chapter 1Where Do Data Come From?Chapter 1 2Thought Question 1From a recent study, researchers concluded that high levels of alcohol consumption resulted in lower graduation rates at colleges. How do you think this study was carried out in order to get these results? Do you think the conclusion is correct? Is there a more reasonable conclusion?Chapter 1 3Thought Question 2It is popular knowledge that for similar jobs men earn more money on average than women, and yet there are cases where some women make more money than some men. Therefore, to determine if men really do earn more, you would need to sample many people of each sex. Suppose we also want to know if, on average, men stay at their current jobs for a longer time period than women. How could you go about trying to determine this? Would it be sufficient to collect data for one member of each sex?... two members of each sex? What information about men’s and women’s measurements would help you decide how many people to measure?Chapter 1 4Thought Question 3In 1997, the Orlando Sentinel released the results of a poll in which more than 90 percent of those people who called in to the paper said that Orlando’s NBA team, the Orlando Magic, should not re-sign its center, Shaquille O'Neal, for the amount of money he was asking. Based on this poll, would you conclude that over 90% of Orlando’s population felt that the team should not re-sign Shaquille O’Neal?Chapter 1 5What is STATISTICS ?Using ‘data’ to draw a conclusion about something unknown.Decision making in the presence of uncertainty.Chapter 1 6What Is “Data”?(better: What are data?)?Pieces of information.Numbers.The above are data only if the information has a meaning attached.Chapter 1 7How 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.Chapter 1 8Common 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 individualChapter 1 9PopulationindividualsChapter 1 10Sampling Frame1923 4 56781017161513141211List of Individuals1234567891011121314151617SampleChapter 1 11Sample SurveymeasurementsdataChapter 1 12List of Individuals1234567891011121314151617Census1923 4 567810171615131412111923 4 56781017161513141211CensusChapter 1 13Case StudyThe Effect of Hypnosison theImmune Systemreported in Science News, Sept. 4, 1993, p. 153Chapter 1 14Case StudyThe Effect of Hypnosison theImmune SystemObjective:To determine if hypnosis strengthens thedisease-fighting capacity of immune cells.Chapter 1 15Case 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.Chapter 1 16Case StudyStudents randomly assigned to one of three conditions–subjects hypnotized, given mental exercise–subjects relaxed in sensory deprivation tank–control group (no treatment)Chapter 1 17Case 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 enhancementChapter 1 18Case StudyThe Effect of Hypnosison theImmune SystemWhat is the population?What is the sample?Chapter 1 19Case StudyThe Effect of Hypnosison theImmune SystemWhat data werecollected?Easy or difficult to achieve hypnotic tranceGroup assignmentPre-study white blood cell countPost-study white blood cell countChapter 1 20Case StudyThe Effect of Hypnosison theImmune SystemIs this an experimentoran observational study?Chapter 1 21Case StudyThe Effect of Hypnosison theImmune SystemDoes hypnosis and mental exercise affect the immune system?Chapter 1 22Case StudyWeight Gain SpellsHeart 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)Chapter 1 23Case StudyWeight Gain SpellsHeart Risk for WomenObjective:To recommend a range of body mass index (a function of weight and height) in terms of coronary heart disease (CHD) risk in women.Chapter 1 24Case 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.Chapter 1 25Case 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.Chapter 1 26Case 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 likelyChapter 1 27Case StudyWeight Gain SpellsHeart Risk for WomenWhat is the population?What is the sample?Chapter 1 28Case StudyWeight Gain SpellsHeart Risk for WomenWhat data werecollected?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.Chapter 1 29Case StudyWeight Gain SpellsHeart Risk for WomenIs this an experimentoran observational study?Chapter 1 30Case StudyWeight Gain


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UK STA 200 - LECTURE NOTES

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