Final - Group Experimental Design Flashcards
Aggregate Matching
Two or more groups, sch as classes, are matched and then randomly assigned to the experimental and control conditions.
Block Matching
A form of matching that groups individuals by their characteristics. Within each group, members are randomly assigned to the experimental and control groups.
comparison groups
In an experiment, a group that has been exposed to a different treatment (or value of the independent variable) than the experimental group.
Compensatory equalization of treatment
A threat to internal validity. When staff providing a treatment to a comparison group feel that it is unfair that the group is not getting the experimental treatment, the staff may work harder or do more more than if there were no experiment.
Compensatory rivalry
A type of contamination in true experimental and quasi-experimental designs that occurs when control group members are aware that they are being denied some advantage and so increase their efforts by way of compensation.
Control Group
In an experiment, a comparison group that receives no treatment.
Debriefing
a researcher’s informing subjects after an experiment about the experiment’s purposes and methods and evaluating subjects’ personal reactions to the experiment.
Diffusion of treatment
A type of contamination in experimental and quasi-experimental designs that occurs when treatment and comparison groups interact and the nature of the treatment becomes known to the comparison group.
Double-blind procedures
An experimental method in which neither the subjects nor the staff delivering the experimental treatments know which subjects are getting the treatment and which are receiving a placebo.
Endogenous Change
A source of causal invalidity that occurs when natural developments or changes in the subjects (independent of the experimental treatment itself) account for some or all of the observed change from pretest to posttest.
Experimental Group
In an experiment, the group of subjects that receives the treatment or experimental manipulation.
History
A sourche of causal invalidity that occurs when something other than the treatment inflences outcome scores; also called an effect of EXTERNAL EVENTS.
insttrumentation
A problem that occurs in experimental designs when the measurement methods are not stable or equivalent.
Internal Validitiy
Criterion necessary to demonstrate causality; it is the ability to rule out all other explanations for the finds.
Matching
A procedure for equating the characteristics of individuals in different comparison groups in an experiment.
Maturation
A threat to internal validity; changes that naturally occur with the passage of time.
Mortality
A problem that occurs in experiments when groups become different because subjects are more likely to drop out o one of the groups for various reasons.
Placebo Effect
A source of treatment misidentification that can occur when subjects who receive a tratment that they consider likely to be beneficial imporve because of that expectation rather than because of the treatment itself.
Posttest
In experimental research, the measurement of an outcome (dependent variable) after an experimental intervention or after a presumed independent variable has changed for some other reason.
Pretest
In experimental resarch, the measurement of an outcome (dependent variable) prior to an experimental intervention or change in a presumed independent variable.
Random assignment
A procedure by which each experimental subject is randomly placed in a group.
Randomization
Random assignment of cases, such as by the toss of a coin.
Reactivity
Changes in an individual or group behavior due to the nature of the experimental conditions or process of measurement.
Resentful demoralization
This proble for experimental designs occurs when comparison group members perform worse that they otherwise might have because they feel that they have been left out of a valuable treatment.
