Ch. 14:Longitudinal & Cross-Sectional Designs and Program Evaluation

Cross-Sectional Study
*A study that captures all of the data for each participant at one time period *A study that tests different age groups at the same time *Tend to think of Cross-Sectional Studies as Between-subjects design -Advantage: all of the age groups can be tested at the same time; very economical -Disadvantage: age confounded with date of birth; therefore you cannot test for cohort effects. *Contrast to Longitudinal study b/c you may look @ different age groups.
Longitudinal Study
*A study in which data on the same people are collected at multiple time periods *A study that tests individuals in a single cohort over the course of time
*Typically within-subjects design w/ repeated measurements, but can be between-subjects *Often quasi-experiments because they involve pre-existing groups *Used extensively in developmental psych.
Cohort and Advantage of a Longitudinal Study
*Cohort – a group that has something in common, often age. Cohorts can range in size ex. Baby Boomers *Advantage: allows for the assessment of changes in variables over time; time is a variable
Disadvantages of Longitudinal Designs
*Takes years to conduct research doesn’t have to be years but does take time *Age confounded with time of testing
*Secular trends *Threats to internal validity
Secular Trends
Def: a change that is taking place in the general population over time ex. Change in technology
Threats to Internal Validity in Longitudinal Designs
*Mortality -selective survival -selective dropout *History *Testing
Cross-Sequential or Time-Lag Designs
*Design tests individuals from 2 or more cohorts at 2 or more times *Design used to help separate developmental, cohort, and secular effects *Popular in social psychology/marketing
*Time-lag effect *You can do the comparisons b/w the cohorts
Time-Lag Effect
The effect resulting from comparing subjects of the same age at different times; shows secular trends
Look at slide
Program Evaluation
*A set of techniques for determining the effectiveness of a social service program *All federally funded programs must be evaluated and we evaluate them with program evaluation
Program Evaluation Continued
*Indicators of effectiveness vary
-There are so many pieces of data to argue that this program is effective or not *Program evaluators work for organization being evaluated or external sponsor (political dimension)
-You have people who are invested to see if this program is actually going to work. People who do evaluation, pass out things, collect data, and fund the evaluation.
Sources of Resistance to Program Evaluation
*Fear that program will be terminated *Fear of losing control of program *Fear that information will be abused *Fear that the wrong measures will be used *Belief that evaluation is pointless *Hopes are too high
Program Evaluation Steps
*Examine the literature *Identify objectives *Determine the methodology *Identify the stakeholders *Ensure type of evaluation matches objectives -Summative -Formative *Present a written report
More descriptive kind. Basically if a program is meeting its goals or not
Getting more at to what extent can we improve the program