probability and significance

• Why is probability important in psychology research?

  It helps manage the risk of errors
• What are the two competing hypotheses in research?

  Null hypothesis (H0) and alternate hypothesis (H1)
• What does the null hypothesis suggest?

  There is no causal relationship between variables
• What does the alternate hypothesis suggest?

  There is a causal relationship between variables
• In an experiment, what is manipulated to observe effects?

  The independent variable
• How did the researcher control for order effects?

  By counterbalancing the conditions
• What does a p-value of 0.05 indicate?

  5% chance results are due to chance
• What does a probability of 0 mean?

  It means an event is impossible
• What does a probability of 1 mean?

  It means an event is certain
• What is a type 1 error?

  Accepting a false alternate hypothesis
• What is a type 2 error?

  Rejecting a true alternate hypothesis
• How can researchers reduce the likelihood of a type 1 error?

  By using a stronger level of significance
• How can researchers reduce the likelihood of a type 2 error?

  By using a weaker level of significance
• How do type 1 and type 2 errors relate to courtroom decisions?

  • Type 1 error: Jury wrongly convicts an innocent defendant.
  • Type 2 error: Jury wrongly acquits a guilty defendant.
• What is the significance of the 0.05 level in psychology research?

  • Accepted probability threshold for significance
  • Indicates a 5% chance results are due to chance