1. Lecture 2: Types of Studies, Target Populations, & Ethical Concerns
CRIM 430
Lecture 2: Types of Studies, Target Populations, & Ethical Concerns

2. Types of Studies
Once you have a research question, the next step is putting together an appropriate research design to answer your question
One of the most important parts of this process is deciding what type of study you will conduct
What type of time dimension does your study require—cross-sectional or longitudinal?
The type of design you choose must “fit” with your research question

3. Cross-Sectional Studies
Cross-sectional: Collection of data at one point in time
Best for exploratory and descriptive studies
Example: U.S. Census or a police survey to discover what the primary concern of citizens is
Strengths
Cost-efficient
Fewer logistic problems
Disadvantages
Tries to understand causal processes based on observations observed at one point in time

4. Longitudinal Studies
Longitudinal studies: Designed to allow observations over a period of time
There are different types of longitudinal studies
Trend, cohort, and panel studies
Strengths
Better for testing causal processes
Allow for more in-depth understanding of behavior
Weaknesses
Expensive
Logistically more complicated and time consuming
Attrition (losing respondents)

5. Types of Longitudinal Studies
Trend studies=examine changes within the general population population over time
Example: UCR
Cohort studies=examine more specific populations as they change over time
Cohorts=a group of people who enter or leave an institution at the same time
Example: Examining job placement success of CSLA graduates by the year they graduated
Panel studies=same set of people are interviewed two or more times over time
Example: NCVS

6. Comparison of Longitudinal Studies
Research topic: Arrests for burglary
A trend study=Examine shifts in burglary arrests during this time using the UCR
A cohort study=Select a group of individuals because of age/entering or leaving institution at the same time & follow over time
A panel study=Select a group of individuals and ask them questions 2+ times over time

7. Direction in Studies
Retrospective research: Asks respondents to recall their past
Potential problems:
Poor memory
Lying
Unavailable or incomplete records
Looking backward has limitations
Prospective research: Begin with a sample and follow their behavior into the future
Can be used within a cross-sectional framework
Sample selection differs and plays a critical role in each approach

8. Approach Comparisons
Prospective: What % of abuse victims later abuse their children?
Time 1
Time 2
Parents
Victims
206 Not Victims (81%)
1 Victim
49 Victims (19%)
9 Victims
Retrospective: What % of abuse victims have parents who were abused?
1 Not Victims
10 Victims
.5%
18%
10%
90%

9. Choosing a Study Type Does your research question imply time?
Can you use a snapshot of data to answer your question or do you need to assess your question over a period of time?
If time is implied in your research question, is it more appropriate to look backward or to look forward in time?
Ultimate selection of a study type will be completed once your research design is selected (I.e., experimental or non-experimental)

10. Identifying a Target Population
Another critical aspect to preparing your research methodology is deciding who your target population will be
Target population=Who is the focus of your study?
Selection criteria=the characteristics that define the boundaries of your target population
Defining a target population is critical to selecting a sample

11. Relationship b/t Population & Sample
Target Population
Sample

12. Units of Analysis Target populations may be (what):
Individuals-data are derived from individuals and used to describe the individuals
Groups-data are grouped into categories and compared across those categories
Organizations-data are grouped by organization and compared across those organizations
Social Artifacts-products of social beings and their behavior are compared to identify patterns
Mixture

13. Avoid Mistakes
Ecological Fallacy: Applying results from group analysis to individuals
Individualistic Fallacy: Applying information related to an individual to groups of individuals

14. Ethical Issues
All research is bounded and defined by professional code of ethics
Social science research is particularly subject to ethical codes because it almost always includes humans subjects
When conducting research, it is necessary to balance the potential benefits from doing the research against the possibility of psychological, emotional, and physical harm

15. IRB
All human subject research conducted at a University must be reviewed and approved by the Institutional Review Board
The IRB ensures that federally defined safeguards are applied in all types of research with humans
Code of Federal Regulations Title 45, Chapter 46, U.S. Department of Health & Human Services
Additional rules apply to two populations considered particularly vulnerable:
Prisoners
Children

16. IRB Safeguards Safeguards include:
Written consent form must be used to request participation in the study
Written list of benefits and costs of participation
Subject must voluntarily participate
Subject must be guaranteed anonymity or confidentiality
Analysis of data in the aggregate
Protection from deceit by researchers