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MAX 201 Quantitative Methods for the Social Sciences

MAX 201 Quantitative Methods for the Social Sciences. Controlling for a Third Variable; Developing a Research Topic. Univariate, bivariate, and multivariate analysis. Most basic data description : statistics applied to one variable: mean, median, percentages.

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MAX 201 Quantitative Methods for the Social Sciences

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  1. MAX 201Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

  2. Univariate, bivariate, and multivariate analysis • Most basic data description: statistics applied to one variable: mean, median, percentages. • Bivariate analysis uses contingency tables to look at two variables at a time. • Introducing a third variable is called controlling or specifying the original relationship.

  3. Controlling for a third variable: sex and auto accidents • Men have more accidents than women (gender is related to accident involvement) • Introduce a third variable: miles driven per year • Gender is related to miles driven (men drive more) • Miles driven is related to accidents (the more you drive, the more likely you are to have an accident).

  4. SEX ACCIDENT Frequency MILES driven SEX ACCIDENT Frequency Sex & accidents: spurious relationship

  5. Control Variable as an Intervening Variable Ind. Var. Dep. Var. Control Variable

  6. Caffeine and Heart Attacks • One study linked caffeine consumption with an increased of heart disease. • Study did not control for a third variable: whether patients in the smoked. • Heavy caffeine consumers also smoke. • Further study revealed that smoking not caffeine was the cause of the heart disease. • Source: Ian Ayres, Super Crunchers. NY: Bantam: 2007: pp 90-91.

  7. Wealthier is Healthier • For countries, a graph of mortality against income reveals that populations of richer countries live longer. • For individuals within a country, higher- income individuals live longer than lower-income individuals. • The relationships are much more complex, however.

  8. Wealthier is Healthier • For countries, public health –sanitation and removal of waste – plays an important role. Big Medicine – vaccination and antibiotics – play a role. Individual care plays a larger role as income grows. • In poor countries, mosquitoes, AIDS, unsafe drinking water and other public health issues play a large role in mortality. • Insecticide will work to some degree on mosquitoes, but eventually mosquitoes develop a resistance. Need to remove open, stagnant pools where mosquitoes breed.

  9. Wealthier is Healthier • For individuals, the relationship between health and income is more complex. • Better utilization of knowledge about health (smoking) and more education may cause health, rather than income directly causing health. • Certain groups experience more stress from discrimination, low-income and that harms health. • Source: David Cutler, Angus Deaton, Adriana Lleras-Muney. “”The Determinants of Mortality.” Journal of Economic Perspectives. 20 (3) 2006: 97-120.

  10. Controlling for a third variable: health care and party id • Controlling for a third variable discussed in the chapter from the Cole book, “Sorting Out Relationships” • Work through that example: • original relationship is support of health care and party identification (10.1) • control variable is income • different possibilities are considered

  11. Party ID and Health Care Reform

  12. Party ID and Health Care Reform

  13. Interpreting the controls • Controlling for a third variable can help you understand the bivariate relationship you’re interested in • Controlling for a third variable can tell you that the original relationship • Is spurious • Is maintained • Differs within categories of the 3rd variable

  14. GSS data and 3-variable relationships • May find spurious relationships • More likely to find specified relationships • Very likely to look at joint impact of two independent variables on a dependent variable

  15. Example • Hypothesis: People with more children will have more conservative or traditional views on childrearing. • These views may differ by gender.

  16. Assignment 8 • Control for third variable and interpret • Find and summarize an article related to your topic • Briefly describe your projected research project.

  17. Citations of Scholarly Articles • Research-based papers very important • In “Refereed” or Peer-reviewed journals • Other sources (Newsweek, Washington Post, NYT, blogs, on-line informational sites) may be used as supplements, but be careful here. Blogs and wikpedia might be simply uninformed opinion. Do they belong in your paper? • Library data bases (e-journals)

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