Inferential Statistics

• What is the purpose of the video?

  Introduction to Chi-squared for psychology students
• What type of statistical test is Chi-squared?

  Inferential statistical test
• What does Chi-squared primarily test?

  Difference in nominal data
• What type of data does Chi-squared use?

  Nominal data
• How can you remember that Chi-squared uses nominal data?

  By associating "Chi" with "Hi" and names
• What design does Chi-squared use?

  Independent groups design
• What does the formula for Chi-squared involve?

  Calculating observed and expected values
• What does "O - E" represent in the Chi-squared formula?

  Observed value minus expected value
• What does squaring the difference in the Chi-squared formula achieve?

  It eliminates negative values
• What does "sigma" represent in the Chi-squared formula?

  Total of all calculated values
• How do you calculate expected values for Chi-squared?

  Using row and column totals
• What is the first step in calculating Chi-squared?

  Label the cells for calculations
• What is the final step in calculating Chi-squared?

  Add all calculated values together
• How do you determine degrees of freedom for Chi-squared?

  Subtract one from rows and columns
• What is the degrees of freedom for a 2x2 study?


  1
• What does a critical value of 3.84 indicate?

  Significance at p < 0.05
• What must the observed value be to reject the null hypothesis?

  Equal or greater than the critical value
• What conclusion is drawn if the Chi-squared value is less than 3.84?

  Accept the null hypothesis
• What does the alternative hypothesis state in this context?

  There would be a difference in behaviors
• What are the steps to calculate Chi-squared?

  1. Label the cells (A, B, C, D)
  2. Calculate expected values using row and column totals
  3. Compute O - E for each cell
  4. Square the result and divide by E
  5. Sum all values to get Chi-squared
  6. Determine degrees of freedom
  7. Compare Chi-squared to critical value
• What are the implications of accepting or rejecting the null hypothesis in Chi-squared tests?

  • Accepting null: No significant difference found
  • Rejecting null: Significant difference found
  • Affects interpretation of results and conclusions
• What is Spearman's rank correlation coefficient used for?

  It tests relationships or correlations
• What type of data does Spearman's rank correlation use?

  Ordinal data as a minimum
• What are the steps in calculating Spearman's rank correlation?

  1. Rank both sets of data
  2. Find the difference between ranks
  3. Square the differences
  4. Sum the squared differences
  5. Multiply by 6
  6. Calculate n and n(n-1)
  7. Multiply by n
  8. Divide the total from step 5 by the total from step 7
  9. Subtract from 1
• What is the first step in calculating Spearman's rank?

  Rank both sets of data
• Why do we square the differences in Spearman's rank calculation?

  To cancel out any minor signs
• If the difference between ranks is -2, what is the squared difference?

  4
• What do we multiply the total squared differences by in Spearman's rank calculation?

  6
• What is the result of multiplying 32 by 6?

  192
• What is the formula for n(n-1) when n is 6?

  30
• What do you get when you multiply 30 by 6?

  180
• What is the critical value for n=6 at p=0.05?

  0.829
• What conclusion is drawn from the comparison of the observed value and critical value?

  No significant effect was found
• What does accepting the null hypothesis imply in this context?

  There is no relationship between testosterone and aggression
• What is the alternative hypothesis in this study?

  • There is a relationship between testosterone and aggression
  • Higher testosterone levels lead to increased aggression
• What is the overall conclusion of the video regarding testosterone and aggression?

  There is no relationship between them
• What statistical test is discussed in the video?

  Man Whitney U
• When would we use the Man Whitney U test?

  For tests of difference with ordinal data
• What types of data are acceptable for the Man Whitney U test?

  Ordinal, interval, or ratio data
• What design is required for the Man Whitney U test?

  Independent groups design