Interpret the key results for Discriminant Analysis

Complete the following steps to interpret a discriminant analysis. Key output includes the proportion correct and the summary of misclassified observations.

Step 1: Evaluate how well the observations are classified

Examine the proportion of observations correctly placed in their true groups to evaluate how well your observations are classified.

Summary of Classification True Group Put into Group 1 2 3 1 59 5 0 2 1 53 3 3 0 2 57 Total N 60 60 60 N correct 59 53 57 Proportion 0.983 0.883 0.950
Correct Classifications N Correct Proportion 180 169 0.939
Key Results: Proportion, Proportion Correct

In these results, overall, 93.9% of observations were placed into the correct group. Group 1 had the highest proportion of correct placement, with 98.3% of the observations correctly placed. Group 2 had the lowest proportion of correct placement, with only 53 of 60 observations, or 88.3%, correctly classified. Therefore, the classification system has the most problems when identifying observations that belong to Group 2.

Step 2: Examine the misclassified observations

Compare the groups that the observations were put into (the predicted group) with the group that was indicated in the grouping column of the worksheet (the true group). If the predicted group does not match the true group, the observation is misclassified. Look for patterns that reveal how observations are most likely to be misclassified.
Note

If you used cross-validation for the analysis, compare the cross-validated (X-val) predicted groups with the true groups.

Summary of Classification True Group Put into Group 1 2 3 1 59 5 0 2 1 53 3 3 0 2 57 Total N 60 60 60 N correct 59 53 57 Proportion 0.983 0.883 0.950
Summary of Misclassified Observations True Pred Squared Observation Group Group Group Distance Probability 4** 1 2 1 3.524 0.438 2 3.028 0.562 3 25.579 0.000 65** 2 1 1 2.764 0.677 2 4.244 0.323 3 29.419 0.000 71** 2 1 1 3.357 0.592 2 4.101 0.408 3 27.097 0.000 78** 2 1 1 2.327 0.775 2 4.801 0.225 3 29.695 0.000 79** 2 1 1 1.528 0.891 2 5.732 0.109 3 32.524 0.000 100** 2 1 1 5.016 0.878 2 8.962 0.122 3 38.213 0.000 107** 2 3 1 39.0226 0.000 2 7.3604 0.032 3 0.5249 0.968 116** 2 3 1 31.898 0.000 2 7.913 0.285 3 6.070 0.715 123** 3 2 1 30.164 0.000 2 5.662 0.823 3 8.738 0.177 124** 3 2 1 26.328 0.000 2 4.054 0.918 3 8.887 0.082 125** 3 2 1 28.542 0.000 2 3.059 0.521 3 3.230 0.479
Key Results: Observation, True Group, Pred Group

Column 2 of the Summary of Classification table shows that 53 observations were correctly assigned to Group 2. However, 5 observations from Group 2 were instead put into Group 1, and 2 observations from Group 2 were put into Group 3. Therefore, 7 of the observations from Group 2 were incorrectly classified into other groups.

The Summary of Misclassified Observations table shows observations 65, 71, 78, 79, and 100 were misclassified into Group 1 instead of Group 2, which was the most frequent misclassification.

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