Lecture Material

• How do experiments make causal statements?

  1. Establish temporal precedence [which means, the cause (independent variable) occurs before the effect (dependent variable)].
  2. Experiments establish covariation [which means, when values of one variable increase (or decrease) as the value of the other also increases (or decreases)].
  3. Experiments eliminate most alternative explanation.
• What does it mean to have experimental control?

  Treat participants in all groups in the experiment identically so that the only difference between groups is the independent variable.
• What does it mean when a study is "internally valid?"

  A study that effectively meets all three criteria for cause and effect is said to have high internal validity.

  1. Establishes temporal precedence.
  2. Establishes covariation.
  3. Eliminates other alternative explanations.
• What are the two issue when choosing a particular method?

  1. Artificiality of Experiments – may limit either the questions that can be addressed or the generality for the results. An overly artificially environment can not be generalised into everyday life.
  2. Ethical and Practical Considerations – Sometimes the experimental method is not a feasible alternative because experimentation would be either unethical or impractical.
• What are the advantages of multiple methods?

  Helpful to investigate a phenomenon to gain better understanding of it. When multiple studies using multiple methods point to the same conclusion, our confidence in the findings are greatly increased.