Expe method
What is experiment?
conditions are controlled
1 or more independent variables
can be manipulated to test a hypothesis
about a dependent variable
Dependent variable - criterion by which the results of the experiment are judged.
Independent variable - any variable that can be manipulated
Experimental treatments - alternative manipulations of the independent variable being investigated
Experimental Group - Group of subjects exposed to the experimental treatment
Control group - subjects that are exposed to the control condition
Test unit - entity whose responses to experimental treatments are being observed or measured
Randomization - assignment of subjects and treatment to groups is based on chance
Constant error (bias) - is error that occurs in the same experimental condition every time the basic experiment is repeated
Extraneous variables - variables other than the manipulated variables that affect the results of the experiment
Demand Characteristics - Experimental design procedures or situational aspects of the experiment that provide unintentional hints to subjects about the experimenters hypothesis
Experimenter bias - effect on the subjects behavior caused by an experimenters presence action or comments
Guinea pig effect - results caused by subject changing normal behavior or attitudes to cooperate with experimenter
Blinding - Technique used to control subjects knowledge of whether or not they have been given the experimental treatment
Constancy of conditions - subjects in experimental & control groups are exposed to identical situations except for differing conditions of the independent variable
Order of presentation - if experimental method requires that the same subject be exposed to 2 or more experimental treatments, error may occur due to order in which the treatment are presented
Counterbalancing - Eliminates the effects of order of presentation
Internal validity - indicates whether the independent variable was the sole cause of the change in the dependent variable
External validity - indicates the extent to which the results of the experiment are applicable to the real world
History effect - influence of events or circumstances outside an experiment on an outcome variable of interest
Cohort Effect - Change in the dependent variable that occurs because members of one experimental group experienced different historical situations than members of other experimental group
Maturation Effect - Effect on experimental results caused by experimental subjects maturing or changing over time
Testing Effect - In before-and-after studies, pretesting may sensitize subjects when taking a test for the 2nd time.
Instrumentation Effect - Caused by a change in the wording of questions, in interviewers, or in other procedures used to measure the dependent variable.
Selection Effect - Sampling bias that results from differential selection of respondents for the comparison groups.
Mortality or Sample Attrition - Results from the withdrawal of some subjects from the experiment before it is completed
One-Group Posttest-only Design - Diagrammed as: X O1
One-Group Pretest-Posttest Design - Diagrammed as: O1 X O2
Posttest-only with Non-equivalent Group Design - Diagrammed as:
Experimental Group X O1
Control Group O2
Single-case Designs - Aims to examine whether an intervention is effective to a particular individual in terms of improvements in learning or behavior
True Experimental Designs - Manipulation of IV, Randomization,Comparison groups
Pretest-Posttest Control Group Design - A.K.A., Before After with Control
Posttest-Only Control Group Design - A.K.A., After Only with Control
Solomon Four-Group Design - Combines pretest-posttest with control group design and the posttest-only with control group design
Quasi-Experimental Designs - researchers cannot achieve complete control over potential confounding variables that can be threats to the internal validity of the study
Time Series Design - Involves periodic measurements on the dependent variable for a group of test units
Statistical Designs - Multiple experiments are conducted simultaneously to permit extraneous variables to be statistically controlled
Latin Square Design - Allows control or elimination of the effect of two extraneous variables
Factorial Design - Used to examine the effects that the manipulation of at least 2 independent variables
main effect - The impact that each independent variable has on the dependent variable is referred to as the ____
interaction effect - The dependent variable may also be impacted by the interaction of the independent variables. This is called the _________