Chapter 9
Maturation effect
A function of time and the naturally occurring events that coincide with growth and experience.
Experimental group
A group of subjects to whom an experimental treatment is administered
Control group
A group of subjects to whom no experimental treatment is administered
Testing effects
A nuisance effects occurring when the initial measurement or test alerts or primes subjects in a way that affects their response to the experimental treatments.
Instrumentation effects
A nuisance that occurs when a change in the wording of questions, a change in interviewers, or change in other procedure causes a change in the dependent variable.
Manipulation check
A validity test of an experiment to make sure that the manipulation does produce differences in the independent variable.
External validity
Accuracy with which experimental results can be generalized beyond the experimental subjects
Confound
An experimental confound means that there is an alternative explanation beyond the experimental variables for any observed differences in the dependent variable
Blocking variable
Categorical variable included in the statistical analysis of experimental data as a way of accounting for variance due to that variable
Systematic or nonsampling error
Occurs if the sampling units in an experimental cell are some-how different than the units in another cell, and this difference affects the dependent variable
History effect
Occurs when a change other than the experimental treatment occurs during the course of an experiment that affects the dependent variable
Mortality effects( sample attrition)
Occurs when some subjects withdraw from the experiment before its is completed
Experimental Condition
One of the possible levels of an experimental variable manipulation
Cohort effect
Refers to a change in the dependent variable that occurs because members of one experimental group experienced different historical situations than members of other experimental groups
Cell
Refers to a specific treatment combination associated with an experimental group
Field experiment
Research project involving experimental manipulation that are implemented in a natural environment
Laboratory experiment
Research project involving experimental manipulation that are implemented in a natural environment in an artificial environment.
Placebo effects
The effects in a dependent variable associated with the psychological impact that goes along with knowledge of some treatment being administered
Main effects
The experimental difference in dependent variable between the difference levels of any single experimental variable
Internal validity
The extent to which experimental variable is truly responsible for any variance in the dependent variable
Randomization
The random assignment of subject and treatment to groups
Subjects
The sampling units for an experiment, usually human participants in research who are subjected to some experimental manipulation.
Test units
The subjects or entries whose responses to the experimental treatment are measured or observed
Experimental treatment
The term referring to the way an experimental variable is manipulated
Within-subject design
involves repeated measures because with each treatment the same subject is measured
demand effects
occurs when demand characteristics actually affect the dependent variable
Interaction effect
Difference in dependent variable means due to a specific combination of independent variable
Between-subject design
Each subject receives only one treatment combination
demand characteristics
Experimental design element or procedure that unintentionally provides subjects with hints about the research hypothesis
Repeated measures
Experiments in which an individual subjects is exposed to more than one level of an experimental treatment