Chapter 7 Flashcards
(19 cards)
Experimental Variable
- manipulated or varied by researcher
- is ALWAYS an independent variable
R
random assignment
G
Group
X
Experimental Variable (independent)
O
Outcome variable (dependent)
experiemental variables
levels of experimental treatment
General Criteria for a well Designed Experiment
Essentially the characteristics that make for a good research design also apply to the design of an experiment.
- Adequate experimental control
- Lack of artificiality (i.e., meaningful application)
- Has a comparison group
- Adequate data to allow for statistical precision
- Uncontaminated data
- No confounding variables
- Representativeness
- Parsimony – mindful of number of variables explored
Construct Validity
Applies to the operational definitions of variables in experiment (construct); concerns that they could be construed for some other construct.
The extent to which a test measures one or more dimensions of a theory or trait.
Statistic Conclusion Validity
Applies to the statistical analysis and whether or not there exists a statistically significant difference between the experiment and control group.
Threats to Internal Validity
- History - fire drill so missed class
- Maturation -
- Testing (memory) - remembers questions from last test
- Instrumentation - same post test given, one doesnt follow directions
- Statistical Regression
- Selection
- Mortality* - dropping out
- Selection-maturation interaction- JHS Students fatigue, HS Student do not during test
Threats to External Validity
**ON EXAM**
- Interaction effect on testing - pretest effects
- Interaction effects of selection biases and the experimental treatment - an effect of some selection factor of intact groups interacting with the experimental treatment that would not be the case if the groups were formed randomly
- Reactive effects of experimental arrangements- effect due to artificial test setting
- Multiple-treatment interference - potential carryover effect of treatments, results cannot be generalized to single treatment.
Threats to Construct Validity
- Inadequate preoperational explication of constructs*
- Mono-operational bias
- Mono-method bias
- Hypothesis-guessing within experimental conditions*
- Confounding constructs and levels of constructs
* All within researchers control
Threats to Statistical Conclusion Validity
- Low statistical power - using sample size that is too small to detect differences
- Violated assumptions of statistical test
- Fishing and the error rate problem-capitalizing on chance findings
- Reliability of measures - using technically inadequate measures
Post-test only control group
contains as many groups as there are experimental treatments, plus a control group
Subjects are only measured after the experimental treatments have been applied
R G1 X1 O1
R G2 X2 O2
R G3 X4 O3
R G4 X4 O4
R G5 – O5
Pretest - posttest control group design
contains as many groups as there are experimental treatments. plus a control group
Subject are measured before and after recieving the experiemental treatments
R G1 O1 X1 O2
R G2 O3 X2 O4
R G3 O5 X3 O6
R G4 O7 – O8
Solomon Four-Group Design
tests on the effects of pretesting
is a combination of the posttest-only control group design and the pretest-posttest control group design
four groups included only on experiment used
R G1 O1 X O2
R G2 03 – O4
R G3 – X O5
R G4 – – O6
Factorial Design
involves two or more independent variables
R G1 X1 Y1 O1
R G2 X1 Y2 O2
R G2 X2 Y1 O3
R G3 X2 Y2 04
Repeated Measures
the same subject is measured more than once on the dependent variable
R G1 X O1-O2-O3
R G2 – O4-O5-O6
