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.

In This Topic

Step 1: Evaluate how well the observations are classified
Step 2: Examine the 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

Observation	True Group	Pred Group	Group	Squared 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.