Chapter 9: Experimental and Quasi-Experimental Designs Flashcards
a priori
From Latin: the former; before the study or analysis
after-only design
An experimental design with two randomly assigned groups – a treatment group and a control group. This design differs from the true experiment in that both groups are measured only after the experimental treatment
after-only nonequivalent control group design
a quasi-experimental design similar to the after-only experimental design, but subjects are not randomly assigned to the treatment or control groups
antecedent variable
a variable that affects the dependent variable but occurs before the introduction of the independent variable
attention control
operationalized as the control group receiving the same amount of “attention” as the experimental group
control
measures used to hold uniform or constant the conditions under which an investigation occurs
dependent variable
in experimental studies, the presumed effect of the independent or experimental variable on the outcome
design
the plan or blueprint for conduct of a study
effect size
an estimate of how large of a difference there is between intervention and control groups in summarized studies
experimental design
a research design that has the following properties: randomization, control, and manipulation
extraneous design (mediating variable)
variable that interferes with the operations of the phenomena being studied
independent variable
the antecedent or the variable that has the presumed effect on the dependent variable
intervening variable
a variable that occurs during an experimental or quasi-experimental study that affects the dependent variable
intervention fidelity
the process of enhancing the study’s internal validity by ensuring that the intervention is delivered systemically to all subjects
manipulation
the provision of some experimental treatment, in one or varying degrees, to some of the subjects in the study
mortality
the loss of subjects from time 1 data collection to time 2 data collection
nonequivalent control group design
a quasi-experimental design that that is similar to the true experiment, but subjects are not randomly assigned to the treatment or control groups
one-group (pretest-posttest) design
Design used by researchers when only one group is available for study. Data are collected before and after an experimental treatment on one group of subjects. In this type of design, there is no control group and no randomization
power analysis
the mathematical procedure to determine the number for each arm (group) of a study
quasi-experimental design
a study design in which random assignment is not used, but the independent variable is manipulated and certain mechanisms of control are used
randomization (random assignment)
a sampling selection procedure in which each person or element in a population has an equal chance of being selected to either the experimental group or the control group
randomized controlled trial (RCT)
a research study using a true experimental design
Solomon four-group design
an experimental design with four randomly assigned groups – the pretest-posttest intervention group, the pretest-posttest control group, a treatment or intervention group with only posttest measurement, and a control group with only posttest measurement
testing
the effects of taking a pretest on the scores of a posttest
time series design
A quasi-experimental design used to determine trends before and after an experimental treatment. Measurements are taken several times before the introduction of the experimental treatment, the treatment is introduced, and measurements are taken again at specified times afterward
treatment effect
the impact of the independent variable/intervention on the dependent variable
true (classic) experiment (pretest-posttest control group design)
In this design, subjects are randomly assigned to an experimental or control group, pretest measurements are performed, an intervention or treatment occurs in the experimental group, and posttest measurements are performed
