Example of a Quasi-Experimental Study: Sex and Spatial Memory

One-Group Posttest Only Design

One-Group Pretest-Posttest Design

Nonequivalent Groups Design

Example of a Quasi-Experimental Study: Anti-Bullying Program

Selection Effect

Comparison of Internal Validity Across Research Designs

Tuskegee Syphilis Study

Elimination of Directionality Problem in Quasi-Experiments

Applications of Quasi-Experimental Research

Causal Limitations of Quasi-Experimental Research

Which of the following is a key characteristic that distinguishes quasi-experimental research from a true experiment?

Match each feature of a quasi-experimental design with the specific role it plays or the consequence it has on the quality of a psychological research study.

A clinical psychologist evaluates the effectiveness of a new mindfulness-based therapy by providing the treatment to all patients at one clinic while patients at a neighboring clinic receive standard care. Because the researcher is manipulating the treatment but is using pre-existing groups rather than assigning individual patients to conditions by chance, this study is best categorized as a(n) _________ research design.

A psychologist is testing the impact of a new peer-mentoring program in a local high school. Arrange the logical sequence of steps the psychologist would take to conduct a study that follows a quasi-experimental design and evaluates the strength of its causal claims.

A researcher claims that their quasi-experimental study provides the same level of confidence in causal conclusions as a true experiment because both designs involve the manipulation of an independent variable. This evaluative claim is scientifically sound.

Although quasi-experimental research offers more control than purely correlational studies, it generally possesses lower internal validity than a true experiment because it lacks random assignment or counterbalancing.

A researcher evaluates a new educational software by implementing it in one classroom and comparing the results to another classroom that continues with the standard curriculum. Which statement best explains why this quasi-experimental design has lower internal validity than a true experiment, yet still provides more control than a purely correlational study?

A psychology instructor asks students to match scenarios with their corresponding design feature. Match each research description to the quasi-experimental design feature or consequence it applies.

An investigator is analyzing the methodological differences between two research proposals. Study A uses random assignment and counterbalancing, whereas Study B implements a comparison condition using pre-existing groups without random assignment. In analyzing their quality, the investigator concludes that Study B generally possesses lower _____ than Study A.

Evaluate the following research design scenarios based on the standard of internal validity and control established in methodology. Arrange them in order from the design that provides the HIGHEST level of internal validity to the design that provides the LOWEST level of internal validity.

Define quasi-experimental research and identify the specific methodological features of a true experiment that it frequently lacks, as well as its position relative to purely correlational and true experimental research regarding internal validity.

Based on the provided scenario, diagnose the type of research methodological design being used and justify why this design possesses lower internal validity compared to a true experiment.

A researcher conducts a study on memory where all participants complete the exact same sequence of tasks, introducing potential order effects. What specific methodological control should the researcher apply to this design to address these order effects and move it closer to a true experiment?