Ch. 10: The Nonexperimental and Quasi-Experimental Strategies Flashcards
similarity between the nonexperimental and quasi-experimental research strategies
involve comparisons of scores from different groups or different conditions
differences between the nonexperimental and quasi-experimental designs
- The nonexperimental design makes little or no attempt to minimize threats to internal validity
- The quasi-experimental design makes some attempt to minimize threats to internal validity and approaches the rigour of a true experiment
key elements of nonexperimental and quasi-experimental designs
- Often look like experiments in terms of their general structure
- Produces groups of scores to be compared for significant differences
- One variable is used to create the groups or conditions to be compared and the second is measured to obtain a set of scores within each condition
- Groups are defined in terms of a specific participant variable or in terms of time
two general categories of nonexperimental and quasi-experimental designs
- between-subjects (nonequivalent group designs)
- within-subjects (pre-post designs)
nonequivalent group design
a research study in which the different groups of participants are formed under circumstances that do not permit the researcher to control the assignment of individuals to groups, and the groups of participants are therefore, considered nonequivalent
is random assignment used in nonequivalent designs?
no, the researcher cannot use random assignment to create groups of participants
what is the main threat to internal validity in nonequivalent group designs
individual differences
Three common examples of nonequivalent group designs
- The differential research design
- The posttest-only nonequivalent control group design
- The pretest-posttest nonequivalent control group design
differential research design
a research study that compares preexisting groups
what type of research design is differential research?
nonexperimental nonequivalent group design
how do researchers assign participants to groups in the differential research design?
using participant characteristics
measurement of the dependent variable in the differential research design
A DV is then measured for each participant to obtain a set of scores within each group
goal of the differential research design
to determine whether the scores of one pre-existing group are consistently different from the scores of another pre-existing group
synonym for the differential research design
ex post facto research because it looks at differences after the fact
similarities between differential and correlational research
- A researcher simply observes two naturally occurring variables without any manipulation
- The results are interpreted in the same way
- Neither allows for a cause-and-effect explanation of a relationship
differences between differential and correlational research
- In differential research, the participant differences in one variable are used to create separate groups and the measurements of the second variable are made within each group. The researcher then compares the measurements for one group with the measurements from another
- In correlational research, the researcher treats all participants as a single group and simply measures the two variables for each individual
- They use different statistical analyses
nonequivalent control group design
uses preexisting groups, one of which serves in the treatment condition and the other in the control condition. The researcher does not randomly assign individuals to the groups
what type of research design is the nonequivalent control group design?
nonexperimental nonequivalent group design
posttest-only nonequivalent control group design
compares two nonequivalent groups of participants. One group is observed (measured) after receiving treatment, and the other group is measured at the same time but receives no treatment
what type of research design is the posttest-only nonequivalent control group design
nonexperimental nonequivalent group design
synonym for a posttest-only nonequivalent control group design
static group comparison
posttest-only nonequivalent control group design annotation
- Annotated using X and O, where X corresponds to the treatment and O corresponds to the observation or measurement
- A R is placed as the first symbol in each line of notation if the study used random assignment
what type of research design is the pretest-posttest nonequivalent control group design?
a quasi-experimental nonequivalent group design
pretest-posttest nonequivalent control group design
compares two non-equivalent groups. One group is measured twice, once before a treatment is administered, and once after. The other group is measured at the same two times but does not receive any treatment
annotation of pretest-posttest nonequivalent control group design
O X O (treatment group)
O O (nonequivalent control group)
benefits of the pretest-posttest nonequivalent control group design
- Allows researchers to determine whether the treatment or some other, time-related factor is responsible for the changes
- The addition of a pretest reduces threats to internal validity associated with individual differences
- Can provide some evidence to support a cause-and-effect relationship