Internal and External Validity Flashcards
What research strategy do you use when examining individual variables?
Descriptive research strategy.
What is the descriptive research strategy?
Describes the current state of a variable(s) and does not examine the relationship between variables. (Not comparing between groups)
What research strategy do you use when examining the relationship of two variables?
Correlational research strategy.
What is the correlational research strategy?
Measure two (or more) variables for every individual/subject in the group and identify correlations between variables. Measures relationship between variables - As one variable changes, does the other variable also change? How does the variable change?
* Positive, negative, curvilinear
No manipulation of any variables
What do you use when examining the relationship by comparing scores for each group? (3)
1) Non-experimental research
2) Quasi-experimental
3) Experimental
What is non-experimental research? (3)
- One variable has two levels/conditions
- Lacks a control group
- No manipulation
What is experimental research?
*Establish cause-and-effect relationships
* Compare 2 or more groups on a dependent variable
* The group is manipulated
* Individuals are randomly assigned to the group
* Has a control group
What is quasi-experimental research?
*Similar to experimental
* Has a control group
* But groups cannot be randomly assigned
* In part because of preexisting participant/subject variable
* Does not provide a definitive answer about cause-effect
Difference between quasi-experimental vs experimental?
Quasi cannot be randomly assigned.
What are the two types of validity and their subgroup?
-Validity of measurement: face validity and construct validity.
-Validity of experiment: Internal validity and external validity
What is internal validity?
The extent to which the observed results represent the truth in the population we are studying.
What is external validity?
How well the outcome of a research study can be expected to apply to other settings.
Validity in nonexperimental research strategies?
- Nonexperimental research allows the researcher to examine the behavior in real-life settings
- Realistic environments offer higher external validity
- Environment is not manipulated or controlled ∴ limited internal validity
Validity in Experimental Research Strategies?
- Experimental research allows careful control of the environment
- Conducted in a controlled and constant lab setting ∴ high internal validity
- Experimental research often conducted in unfamiliar
environments, so harder to generalize beyond the experimental setting ∴ limits external validity
Threats to external validity? (3)
- Generalizing across participants or subjects
- Generalizing across study features
- Generalizing across different measures
What is generalizing across participants or subjects? (5)
- Selection bias
- Convenience sample
- Volunteer bias
- Participant characteristics
- Cross-species generalization
What is generalizing across study features? (3)
- Novelty effects
- Multiple treatment interference
- Experimenter characteristics
What is generalizing across different measures? (2)
- Sensitization
- Timing of measurement
Threats to internal validity? (2)
1) Obscuring variables
2) Confounding variables
What are confounding variables? (4)
An unmeasured variable that influences both the supposed cause and effect
* Assignment bias
* Environmental variables
* Time-related variables
* Observer bias
What are obscuring variables?
Variables that can cause null results or misses.
* Ineffective manipulation
* Measurement error
* Excessive variation in data
What are the criteria for generalization? (3)
- Controlled comparison rule:
* When comparing data between experimental and control groups, the only difference must be the independent variable - Sampling rule
* Adequate sample size to control for random sampling error and unbiased sample so it is representative of the population - Operational definitions rule
* Determines what principles can be generalized
* Single experiment only allows generalization within specific terms of the operational definition
What are exact replicas?
Repeat the experiment, get the same results, and increase confidence in the findings.
What are conceptual replications?
The same construct, different experiments/methodology, get consistent results and conclusions get better generalized to entire constructs.
