Probability and significance

• Null hypothesis

  No difference between conditions
• Alternative hypothesis

  There is a difference between conclusions.
• Level of significance

  • 0.05/5%
• Use of tables of critical values

  1. One tailed (Directional hypothesis) or two tailed (non-directional hypothesis)?
  2. Number of participants in study (N) or degrees of freedom.
  3. Level of significance.
• Type 1 error

  • Incorrect rejection of true null hypothesis
  • False positive
  • Researcher claims to have found significant difference or correlation when one doesn’t exist.
• Type 2

  • Failure to reject a false null hypothesis
  • False negative
  • There is significant difference.