Longitudinal Research

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Lecture 11

• Longitudinal Research

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Cross-sectional vs. Longitudinal(p. 212)

• Cross-sectional research data are collected at
  only one point in time
• Longitudinal research data are collected at
  different points in time

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Types of Longitudinal Studies(pp. 213-222)

• Trend Studies
• Most common type of longitudinal study
• Provide information about net changes at an
  aggregate level
• Sample different groups of people at different
  times from the same population

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• Ex)
• presidential election
• satisfaction with the presidents performance
• demographic trends in the TV viewing habits of
  adults from the 1960s to the 1990s
• how advertising students change their perceptions
  of TV commercials as they progress through
  college

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Advantages Disadvantages of Trend Studies (pp.
213-214)

• Valuable in describing long-term changes in a
  population
• Secondary analysis is possible (get data from
  data archives)

• If data are unreliable, false trends will show up
  in the results

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2. Cohort Analysis

• Cohort
• To the Romans one of the 10 divisions of a
  military legion
• For research purpose any group of individuals
  who are linked in some way or who have
  experienced the same significant life event (ex.
  birth, marriage, education) within a given period

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2. Cohort Analysis

• Any study in which some characteristic of one or
  more cohorts is measured at two or more points in
  time
• Attempts to identify a cohort effect
• Ex) How cohorts of advertising students at SJSU
  change their perceptions of TV commercials as
  they progress through college

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Advantages Disadvantages of Cohort Analysis
(pp. 217-218)

• Provides insight into the effects of maturation
  and social, cultural, and political change
• Can be used with either original data or
  secondary data
• Highly flexible (compared to panel studies)

• As a cohort grows older, many of its members die

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3. Panel Studies

• Measure the same sample of respondents at
  different points in time
• Can reveal information about both net change and
  gross change in the DVs
• Can reveal shifting attitudes and patterns of
  behavior that might go unnoticed with other
  research approaches
• Produce data suitable for sophisticated
  statistical analysis and enable researchers to
  predict cause-and-effect relationships

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Advantages Disadvantages of Panel Studies (pp.
218-220)

• Useful in answering questions about the dynamics
  of change
• Help solve the problems normally encountered when
  defining a theory based on a one-shot case study

• Panel members are difficult to recruit
• The problem of mortality (members drop out)
• Respondents become sensitized to measurement
  instruments