____ is the key to controlling the outcomes from experimental research.
design
6 general issues in experimental design:
Internal validity is …
the basic minimum without which any study is not interpretable
Internal validity is the extent to which the results of a study can:
- eliminate any rival hypothesis or events influencing the study
To gain internal validity, the researcher attempts to control and/or eliminate possible _____ variables.
extraneous
Internal validity is particularly important in ______ studies as well as other studies that establish _____-_____ or _____ _____.
When we think the independent variable produces a change in the dependent variable, what do we have to make sure of?
Main threat in internal validity:
unmeasured process accounting for the observed results
Secondary threat in internal validity:
responses do not correctly reflect underlying dimensions
How to minimize threats to internal validity:
3 main categories to threats to internal validity:
Single-group threats:
a threat to internal validity that occurs in a study that uses only a single program or treatment group and no comparison or control
Multiple-group threats:
an internal validity threat that occurs in studies that use multiple groups
Social threats:
an internal validity threat that arise because social research is conducted in real-world human contexts where people will react to not only what affects them, but also to what is happening to others around them
Types of single-group threats:
History (single-group threat):
Maturation (single-group threat):
Testing (single-group threat):
the effects of one test on subsequent administrations of the same test
Instrumentation (single-group threat):
changes in instrument calibration, including lack of agreement within and between observers
Mortality:
loss of participants from comparison group for nonrandom reasons
Regression:
the fact that groups selected based on extreme scores are not as extreme on subsequent testing
Multiple group threats to validity is ____ ____:
- any factor other than the program that leads to posttest differences between groups
Multiple-group threats types:
Selection-history:
A threat to internal validity that results from any other event that occurs between pretest and posttest that the groups experience differently