100-101

Longitudinal Studies

Longitudinal studies involve observing subjects over an extended time period.
Example: Researchers conducting interviews with the same group every six months for five years.
Other examples include evaluating changes in crime reports or prison inmate numbers over time.

Trend Studies: Focus on changes within a general population over time.
- Example: Comparing FBI Uniform Crime Report figures from 1960 to 2010, analyzing crime increases and decreases.
- Trends can also examine how changes in laws affect imprisonment rates.
Cohort Studies: Examine specific populations (or cohorts) and their changes over time.
- Cohorts can be defined by age, such as people born during the 1990s.
- Example: Wolfgang et al. (1972) studied all males born in 1945 in Philadelphia, tracking delinquency and school performance.
Panel Studies: Involve repeated observations on the same subjects over time.
- Example: The National Crime Victimization Survey (NCVS) interviews households multiple times to assess crime victimization rates.
- Panel studies are useful for evaluating program effectiveness by comparing similar subjects before and after intervention.

Longitudinal studies can be costly and complicated to conduct.
Panel attrition is a notable issue where participants may drop out over time, potentially skewing results and affecting conclusions about treatment effectiveness.

Longitudinal conclusions may still be drawn from cross-sectional data using logical reasoning.

Research by Martin Killias (1993) compared gun ownership rates to gun-related violence.
Distinction in interpretability: Causation in gun suicides is clearer than in gun homicides.
Example analysis highlights reliance on available data to infer potential causal relationships.

Retrospective Research: Involves recalling past experiences or behaviors.
- Example: Studying recidivism by examining the delinquency history of current prison inmates.
- Caution: Memory faults and incomplete records can undermine findings.
Selection bias is a significant risk, on how participants are chosen can impact conclusions.
Example of investigating intergenerational violence by analyzing backgrounds of child abuse victims in court settings.
- Hypothesis examination on the transmission of abuse across generations based on family backgrounds, yielding a high correlation with past abuse among parents.