Lecture 5 Expiremental Desings Flashcards
(20 cards)
Key Components of the Classical Experiment
Independent and Dependent Variables
Pretesting and Posttesting
Experimental and Control Groups
Random Assignment:
What is Pretesting
Measures the dependent variable before introducing the independent variable.
What is Posttesting
Measures the dependent variable after exposure to the independent variable.
What is a Experimental Group?
Exposed to the IV (Recives the Treatment
What is a control group?
Not Exposed to the IV (Does not receive treatment
What is Random Assignment
Participants are randomly assigned to either the experimental or control group.
This ensures groups are similar before the experiment, reducing bias.
What are the Criteria for Causality
- Empirical association
- Temporal order
- Non-spuriousness
What are the threats to internal Valditiy
History
Maturation
Testing
Instrumentation
Casual Time Order
Regression to the Mean
Selection Bias
Mortality
Diffusion of Treatment
Compensatory Treatment
Compensatory Rivalry
How is HISTORY a threat to internal validity?
External events may occur during the course of the experiment that confound the experimental results.
How is MATURATION a threat to internal validity?
because it refers to natural changes in participants over time that could influence the results of a study
How is TESTING a threat to internal validity?
The process of testing and retesting may influence participant behaviour - introduce bias or foreknowledge
Only a concern when there are multiple testing points
How is INSTRUMENTATION a threat to internal validity?
Changes in the measurement tools or process during the study
How is CAUSAL TIME ORDER a threat to internal validity?
Inability to distinguish order of IV and DV can confound results
How is STATISTICAL REGRESSION a threat to internal validity?
tendency for extreme scores to shift towards the overall mean in subsequent testing - changes may be due to statistical regression rather than IV
How is SELECTION BIAS a threat to internal validity?
How participants are selected may lead to differences between the sample and population
How is MORTALITY (ATTRITION) a threat to internal validity?
Participants drop out of the study/do not complete the study
How is COMPENSATORY RIVALRY a threat to internal validity?
Control group may attempt to compensate or ‘keep up’ with the treatment group in their results
How is DIFFUSION OF TREATMENT a threat to internal validity?
The experimental group may ‘contaminate’ the control group when communicating
How is COMPENSATORY TREATMENT a threat to internal validity?
The control group is deprived of something considered to be of value and the researchers consciously or subconsciously try to ‘make it up’ to them
