Inferential Statistics – Critical Values; Type 1 / 2 Errors

• What must a psychologist design before starting a study?

  An alternative hypothesis
• What does the alternative hypothesis state?

  The IV will affect the DV
• What does the null hypothesis state?

  The IV will not affect the DV
• What must be conducted after completing a study?

  A statistical test
• What does a statistical test estimate?

  The probability results occurred due to chance
• What is a calculated value?

  The result obtained from a statistical test
• What do you compare the calculated value against?

  A critical values table
• What does checking the calculated value against the critical value determine?

  The level of significance
• What does a significance level of 0.10 indicate?

  10% probability due to chance
• What does a significance level of 0.05 indicate?

  5% probability due to chance
• What is the accepted level of significance in psychology?

  P ≤ 0.05
• What happens if results reach the 0.05 significance level?

  You can accept the alternative hypothesis
• What do psychologists check if findings are significant at the 5% level?

  If they are significant at the 1% level
• When is a more stringent significance level like 1% used?

  When accuracy is very important
• What is a Type 1 error?

  Accepting the alternative hypothesis incorrectly
• Why is a Type 1 error referred to as a false positive?

  It claims a significant difference exists when it doesn't
• When is a Type 1 error more likely to occur?

  When significance level is not strict enough
• What is a Type 2 error?

  Rejecting the alternative hypothesis incorrectly
• When is a Type 2 error more likely to occur?

  When significance level is set too strictly
• What significance level is frequently used to avoid errors?

  5%