Probability and levels of significance

  1. For what are statistical tests used?
    In order to decide whether any pattern found in a set of data is significant, or whether it is down to chance
  2. What is significance?
    Whether or not there is a low probability that chance factors were responsible for any observed difference, correlation or association in the variables tested
  3. What is probability?
    The numerical measurement of the chance of something happening
  4. What is the minimum acceptable probability probability for significance of the P-value in Psychology?
    If there is less than a 5% or 0.05 chance
  5. What is a type 1 error?
    The results are deemed to be significant when they are not due an excessively large P value
  6. What is a type 2 error?
    The results are deemed insignificant when they are significant due to excessively small P values
  7. How can one find the critical value for a set of results?
    • Take into account the size of the sample and the minimum acceptable P value 
    • Select from the table accordingly
  8. In order for significance to be achieved at a chosen level, what must occur?
    The calculated value must be equal to or greater than the critical value
  9. What occurs if the results collected are deemed to be significant?
    • There is less than 5% probability that the results collected were due to chance 
    • The hypothesis is accepted and the null rejected
  10. What occurs if the results are deemed insignificant?
    • There is more than 5% probability that the results occurred due to chance 
    • The null hypothesis is rejected
  11. What 3 things should be considered before answering a question on significance?
    • Should the hypothesis be rejected?
    • Why should the hypothesis be rejected/accepted (refer to the critical and calculated values)?
    • Is the researcher likely to have made a type 1 or 2 error?
Card Set
Probability and levels of significance
AQA PSYB4 Research methods