Causal-Comparative Research

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Causal-ComparativeResearch
July 23, 2001 EAF 410
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What is it?

• Associational
• Differences between/among groups
• Categorical data
• Differences already exist
• Ex post facto
• Much research in medicine sociology

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Examples

• What are the effects of teacher gender on student
  behavior
• How are administrative decisions affected by
  gender

• What causes students to join the glee club?
• How are teaching styles affected by graduate
  studies?

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Type 1

• Exploration of effects caused by membership in a
  group
• What differences in student behavior are caused
  by gender?

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Type 2

• Studies causes of group membership
• Why do ISU students enroll in EAF 410 during the
  summer session?

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Type 3

• Studies the consequences of an intervention
• How do students who have taken EAF 410 evaluate
  research articles?

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Causal Link Tentative

• Does gender cause differences?
• Girls read better
• Boys are disciplined more
• Other probable links in the causal chain

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Basic Approach

• Noted difference between two groups
• Look for causes/consequences

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Similarities with Correlational Research

• Associational
• Attempt to explain phenomena
• Often lead to experimental research
• Dont allow variable manipulation
• Attempt to explore causation

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Similarities with Correlational Research

• Causal-Comparative
• -compare groups
• -categorical variable(s)
• -crossbreak tables

• Correlational
• -individual scores
• -quantitative variables
• -scatterplots r

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Steps Involved

• Identify clarify research problem
• Several alternative hypotheses
• Select subjects (groups)
• Homogenous on some variables
• Instrumentation
• No limits

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Steps Involved(continued)

• Design
• Groups differ on specific variable
• Groups compared on other variable(s)

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Evaluating Threats

• What other factors affect the comparison
  variable?
• What is the likelihood of the groups differing on
  these factors?
• Evaluate threats on likelihood of their effect
  and plan to control.

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Survey Research

• July 23, 2001
• EAF 410

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Three Characteristics

• Information collected to describe
• Information collected by asking questions
• Information collected from a sample

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Major Purpose

• To describe the characteristics of a population
• Not so concerned about why
• Concerned about what is

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Types of Surveys

• Cross-sectional Study
• information collected at just one point in time
• Longitudinal Study
• information collected at different points in time

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Types of Longitudinal Studies

• Trend
• Different samples
• Population may change
• Cohort
• Different samples
• Population doesnt change

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Types of Longitudinal Studies (continued)

• Panel
• Same sample
• Population doesnt change

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Steps in Survey Research

• Clearly define objectives
• Construct clear questions
• Sample (unit of analysis)
• Collect data
• live to a group
• mail
• phone
• face-to-face interviews

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Preparing the Instrument

• Not too long
• Questions easy to answer
• Carefully worded
• can be asked as written
• will mean same to all
• can be answered
• will be answered

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Types of Questions

• Closed-ended
• answers provided
• Open-ended
• respondent provides answers

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Suggestions for Closed-Ended Questions

• Unambiguous
• Simple focus
• Short
• Common language
• Unbiased terms
• Not leading questions
• No double negatives

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Suggestions for Questions

• Try them out on a similar sample
• Make them look good
• Have follow-up questions
• contingency questions -- contingent on answer to
  previous question

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Nonresponse

• Some will not return survey
• Some items will not be answered
• Can use random replacement