Running the Analysis

  1. To run a GLM Repeated Measures analysis, from the menus choose:

    Analyze > General Linear Model > Repeated Measures...

    Figure 1. GLM Repeated Measures Define Factors dialog box
    GLM Repeated Measures Define Factors dialog box
  2. Type week as the within-subject factor name.
  3. Type 4 as the number of levels.
  4. Click Add.
  5. Type sales as the measure name.
  6. Click Add.
  7. Click Define.
    Figure 2. GLM Repeated Measures main dialog box
    GLM Repeated Measures main dialog box
  8. Select SALES.1: Units sold in thousands through SALES.4: Units sold in thousands (when variables are listed in file order) as within-subjects variables.
  9. Select Market ID and Promotion as between-subjects factors.
  10. Click Model in the GLM Repeated Measures dialog box.
    Figure 3. Model dialog box
    Model dialog box
  11. In the Model dialog box, select Type IV from the Sum of squares dropdown list.

    The cell frequencies for the layout of Market ID and Promotion * Market ID are unbalanced, so using the Type IV sums of squares is recommended. Further, Promotion * Market ID has empty cells, which will result in reduced degrees of freedom for this effect.

  12. Click Continue.
  13. Click Plots in the GLM Repeated Measures dialog box.
    Figure 4. Profile Plots dialog box
    Profile Plots dialog box
  14. Select week as the factor to place on the horizontal axis.
  15. Select promo as the factor to define separate lines in the plot.
  16. Click Add.
  17. Select week as the factor to place on the horizontal axis.
  18. Select marketid as the factor to define separate lines in the plot.
  19. Click Add.
  20. Click Continue.
  21. Click Options in the GLM Repeated Measures dialog box.
    Figure 5. Options dialog box
    Options dialog box
  22. In the Options dialog, select Estimates of effect size, SSCP matrices, and Homogeneity tests in the Display group.
  23. Click Continue.
  24. Click OK in the GLM Repeated Measures dialog box.

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