Longitudinal Studies• The ultimate Goal for many extension faculty is to

implement programs that result in permanent, positive change in human social behavior.

• There is one tool that must be utilized if you are to accomplish this goal. This is a longitudinal study. ONLY longitudinal studies can help you determine if changes are persistent across time, maturation and other environmental factors.

Longitudinal Studies• Purpose

• To show trends across time (i.e., as children attend school, they become increasingly competent in their social skills.)

• To document change in individual behavior and/or attitudes across time (i.e., Fred gets smarter as he gets older.)

• To compare individuals across time. (i.e., Girls do relatively well to boys in school, and the academic gap increases across time.)

Secondary Longitudinal Data Sets• There are a number of national longitudinal data sets that

researchers may access. Some of the ones that may be of interest to 4-H and extension faculty include:

• National Longitudinal Survey of Youth

• Adolescent Health Data Set

• Panel Study of Income Dynamics

Surveys, Case Studies and Longitudinal Studies

• Texas Service Learning Study as an Example

• Case Studies

Different Service Learning Schools were selected. Each year for several years, numerous aspects of their programs were studied. The sensitizing concept was “impact” of service learning on students across time. Service learning materials were collected from teachers. Teachers and students were surveys. Comparisons were made across schools and across times.

• Surveys

• A random sample was drawn, and surveys were constructed. Students were surveyed while in first, second, third, fourth and fifth grades. With minor modifications, the same survey was administered every year. Results were then compared across time to determine if participation in Service Learning may have a cumulative impact across time.

Example of a FAMOUS Longitudinal Field Trial

The Perry Preschool Field Experiment/Trial

In the 1960s, low income children in the US went to Head Start.

Studies were done to evaluate the program. First researchers compared the IQ scores of the Head Start group to a control group. See the following slide for the results.

Parents and researchers felt IQ was not a good and valid indicators of the impact of Head Start. A consortium of researchers selected small subgroup of Head Start students and compared them to a control group over 19 years. See slide 7.

Once they evaluated the program, they calculated the savings, to the government, of Head Start. See slide 8.

Field Trials or Experiments

IQ

The Head Start Program - A Famous Field Experiment

Experiments and Longitudinal Studies

• Field Trials or Experiments

• The following slide shows the results of this longitudinal study when students reach the age of 19. These same academic and social success indicators measured actual behavior and continued to be tracked over their lifetime. The indicators included:

• Arrest rates• Pregnancy rates• Various measures of school success and advancement (i.e., grade

advancement, graduation rates etc.,)• Employment rates• Crime rates

Schooling Success

High School Graduation or GED

College or Vocation

Functional Competence

Classified as Mentally Retarded

Years in Special Education

School Responsibility

Detained or Arrested

Teen Pregnancy

Socioeconomic Success

Employed

Received Welfare

Slide 9

Experiments and Longitudinal Studies

• The Perry Preschool Program

• The Control and Experimental Groups were compared on these indicators across time (i.e., academic success was compared across these groups across time to see if the difference noted in the first years decreased, increased or remained the same across time).

• The indicators were compared across time for the Experimental Group (i.e., academic success was compared across time to see if the “impact” of going to preschool decreased with time).

Policy Implications

This study had tremendous policy implications. The group (e.g., The Perry Preschool Program) was part of the Head Start Program. Partly, as a result of this research, Head Start continues to receive support and resources from the federal government to educate low-income preschool children.

Strengthens and Weaknesses of Longitudinal Data

Strengths Allows you to assess the persistence of impacts across

time and place. Allows you to assess how time, maturation and other

environmental factors can influence impacts across time.

Weaknesses Time consuming Expensive Attrition rates over time can lead to same sample sizes

Power Point Created by:

Dr. Carol Albrecht

carol.albrecht@usu.edu 979-777-2421

For More Information

Contact:

Assessment Specialist

USU Extension