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

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

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

MAX 201MAX 201Quantitative Methods for Quantitative Methods for

the Social Sciencesthe Social Sciences

Controlling for a Third Controlling for a Third Variable;Variable;

Developing a Research TopicDeveloping a Research Topic

Page 2: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Univariate, bivariate, and Univariate, bivariate, and multivariate analysismultivariate analysis

Most basic data descriptionMost basic data description: statistics : statistics applied to one variable: mean, median, applied to one variable: mean, median, percentages.percentages.

Bivariate analysisBivariate analysis uses contingency uses contingency tables to look at two variables at a time.tables to look at two variables at a time.

Introducing a Introducing a third variablethird variable is called is called controlling or specifying the original controlling or specifying the original relationship.relationship.

Page 3: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Controlling for a third Controlling for a third variable: sex and auto variable: sex and auto

accidentsaccidents Men have more accidents than women Men have more accidents than women

(gender is related to accident involvement)(gender is related to accident involvement) Introduce a third variable: miles driven per Introduce a third variable: miles driven per

yearyear Gender is related to miles driven (men drive Gender is related to miles driven (men drive

more)more) Miles driven is related to accidents (the more Miles driven is related to accidents (the more

you drive, the more likely you are to have an you drive, the more likely you are to have an accident).accident).

Page 4: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Sex & accidents: spurious Sex & accidents: spurious relationshiprelationship

SEXSEX

ACCIDENT ACCIDENT FrequencyFrequency

MILES drivenMILES driven

SEXSEX

ACCIDENT FrequencyACCIDENT Frequency

Page 5: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Control Variable as an Control Variable as an Intervening Variable Intervening Variable

Ind.

Var.ControlVariable

Dep.Var.

Page 6: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Caffeine and Heart AttacksCaffeine and Heart Attacks One study linked caffeine consumption with an One study linked caffeine consumption with an

increased of heart disease. increased of heart disease. Study did not control for a third variable: Study did not control for a third variable:

whether patients in the smoked.whether patients in the smoked. Heavy caffeine consumers also smoke.Heavy caffeine consumers also smoke. Further study revealed that smoking not Further study revealed that smoking not

caffeine was the cause of the heart disease.caffeine was the cause of the heart disease. Source: Ian Ayres, Super Crunchers. NY: Source: Ian Ayres, Super Crunchers. NY:

Bantam: 2007: pp 90-91. Bantam: 2007: pp 90-91.

Page 7: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Wealthier is HealthierWealthier is Healthier For countries, a graph of mortality For countries, a graph of mortality

against income reveals that against income reveals that populations of richer countries live populations of richer countries live longer. longer.

For individuals within a country, For individuals within a country, higher- income individuals live longer higher- income individuals live longer than lower-income individuals. than lower-income individuals.

The relationships are much more The relationships are much more complex, however. complex, however.

Page 8: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Wealthier is HealthierWealthier is Healthier

For countries, public health –sanitation and removal For countries, public health –sanitation and removal of waste – plays an important role. Big Medicine – of waste – plays an important role. Big Medicine – vaccination and antibiotics – play a role. Individual vaccination and antibiotics – play a role. Individual care plays a larger role as income grows. care plays a larger role as income grows.

In poor countries, mosquitoes, AIDS, unsafe drinking In poor countries, mosquitoes, AIDS, unsafe drinking water and other public health issues play a large water and other public health issues play a large role in mortality. role in mortality.

Insecticide will work to some degree on mosquitoes, Insecticide will work to some degree on mosquitoes, but eventually mosquitoes develop a resistance. but eventually mosquitoes develop a resistance. Need to remove open, stagnant pools where Need to remove open, stagnant pools where mosquitoes breed. mosquitoes breed.

Page 9: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Wealthier is HealthierWealthier is Healthier

For individuals, the relationship between For individuals, the relationship between health and income is more complex. health and income is more complex.

Better utilization of knowledge about Better utilization of knowledge about health (smoking) and more education may health (smoking) and more education may cause health, rather than income directly cause health, rather than income directly causing health. causing health.

Certain groups experience more stress Certain groups experience more stress from discrimination, low-income and that from discrimination, low-income and that harms health. harms health.

Source: David Cutler, Angus Deaton, Adriana Lleras-Muney. “”The Source: David Cutler, Angus Deaton, Adriana Lleras-Muney. “”The Determinants of Mortality.” Journal of Economic Perspectives. 20 Determinants of Mortality.” Journal of Economic Perspectives. 20 (3) 2006: 97-120.(3) 2006: 97-120.

Page 10: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Controlling for a third Controlling for a third variable: health care and variable: health care and

party idparty id Controlling for a third variable Controlling for a third variable

discussed in the chapter from the Cole discussed in the chapter from the Cole book, “Sorting Out Relationships”book, “Sorting Out Relationships”

Work through that example:Work through that example: original relationship is support of health original relationship is support of health

care and party identification (10.1)care and party identification (10.1) control variable is income control variable is income different possibilities are considereddifferent possibilities are considered

Page 11: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Party ID and Health Care ReformParty ID and Health Care Reform

Support Health Care Reform

Republican Democrat Totals

No 73 37 110

Yes 67 123 190

Totals 140 167 300

Gamma = 0.57 Democrats in general support health care reform; republicans show no discernable (statistical) pattern of support or

opposition.

Page 12: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Party ID and Health Care ReformParty ID and Health Care ReformIncome: Low Income: High

Support Health Care

R D Totals R D Totals

No 33 27 60 40 10 50

Yes 27 113 140 40 10 50

Totals 60 140 200 80 20 100

Gamma = 0.67 Gamma = 0.00

Low-income democrats support health care reform more than lower-income republicans do; high-income democrats and republicans show no relationship between party affiliation and support for health care reform.

Page 13: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Interpreting the controlsInterpreting the controls Controlling for a third variable can help Controlling for a third variable can help

you understand the bivariate you understand the bivariate relationship you’re interested inrelationship you’re interested in

Controlling for a third variable can tell Controlling for a third variable can tell you that the original relationshipyou that the original relationship Is spuriousIs spurious Is maintainedIs maintained Differs within categories of the 3rd variableDiffers within categories of the 3rd variable

Page 14: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

GSS data and 3-variable GSS data and 3-variable relationshipsrelationships

May find spurious relationshipsMay find spurious relationships More likely to find specified More likely to find specified

relationshipsrelationships Very likely to look at Very likely to look at joint impactjoint impact of of

two independent variables on a two independent variables on a dependent variabledependent variable

Page 15: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

ExampleExample

Hypothesis: People with more Hypothesis: People with more children will have more conservative children will have more conservative or traditional views on childrearing.or traditional views on childrearing.

These views may differ by gender.These views may differ by gender.

Page 16: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

# of children * Child Suffers if Mom Works Crosstabulation

294 315 609

48.3% 51.7% 100.0%

147 108 255

57.6% 42.4% 100.0%

441 423 864

51.0% 49.0% 100.0%

0-2

3 or more

# of children

Total

Agree Disagree

Child Suffers if MomWorks

Total

Page 17: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

RESPONDENTS SEX * Child Suffers if Mom Works Crosstabulation

218 146 364

59.9% 40.1% 100.0%

224 277 501

44.7% 55.3% 100.0%

442 423 865

51.1% 48.9% 100.0%

MALE

FEMALE

RESPONDENTSSEX

Total

Agree Disagree

Child Suffers if MomWorks

Total

Page 18: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

# of children * Child Suffers if Mom Works * RESPONDENTS SEXCrosstabulation

158 113 271

58.3% 41.7% 100.0%

59 33 92

64.1% 35.9% 100.0%

217 146 363

59.8% 40.2% 100.0%

136 202 338

40.2% 59.8% 100.0%

88 75 163

54.0% 46.0% 100.0%

224 277 501

44.7% 55.3% 100.0%

0-2

3 or more

# of children

Total

0-2

3 or more

# of children

Total

MALE

FEMALE

Agree Disagree

Child Suffers if MomWorks

Total

Page 19: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Assignment 8Assignment 8

Control for third Control for third variable and variable and interpretinterpret

Find and summarize Find and summarize an article related to an article related to your topicyour topic

Briefly describe Briefly describe your projected your projected research project. research project.

Page 20: MAX 201 Quantitative Methods for the Social Sciences Controlling for a Third Variable; Developing a Research Topic

Citations of Scholarly Citations of Scholarly ArticlesArticles

Research-based papers very important Research-based papers very important In “Refereed” or Peer-reviewed journalsIn “Refereed” or Peer-reviewed journals Other sources (Newsweek, Washington Other sources (Newsweek, Washington

Post, NYT, blogs, on-line informational Post, NYT, blogs, on-line informational sites) may be used as supplements, but be sites) may be used as supplements, but be careful here. Blogs and wikpedia might be careful here. Blogs and wikpedia might be simply uninformed opinion. Do they simply uninformed opinion. Do they belong in your paper?belong in your paper?

Library data bases (e-journals) Library data bases (e-journals)