SOME BASIC CONCEPTS:
1. Independent and Dependent variables
2. Extraneous variable
3. Control
4. Confounded relationship
5. Research hypothesis
6. Experimental and Control group
7. Treatments
8. Principles of experimental design
8.1 Replication
8.2 Randomization
8.3 Local control
The method to assess effect of independent variable (manipulated by researcher) on dependent variable in controlled conditions (making other variables constant or controlled in order to prevent them from influencing the dependent variable and confusing the result.
Types of experiments:
True experiment: In a true experiment, subjects are randomly assigned to the treatment conditions (levels of the independent variable). The only differences in the groups would be due to chance. True experiments are excellent for showing a cause-and-effect relationship.
There are three criteria that must be met in a true experiment
- Control group and experimental group
- Researcher-manipulated variable
- Random assignment
Quasi-experiment:
Quasi-experiments are sometimes called natural experiments because membership in the treatment level is determined by conditions beyond the control of the experimenter (subjects are already in the box). An experiment may seem to be a true experiment, but if the subjects have NOT been randomly assigned to the treatment condition, the experiment is a quasi- experiment (quasi = seeming, resembles).
Quasi-experiments are sometimes called natural experiments because membership in the treatment level is determined by conditions beyond the control of the experimenter (subjects are already in the box). An experiment may seem to be a true experiment, but if the subjects have NOT been randomly assigned to the treatment condition, the experiment is a quasi- experiment (quasi = seeming, resembles).
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