Basic Difference Between Clustering Analysis and Discriminant analysis

Hello everyone.....its been long time since we had a discussion on discriminant analysis in class.

Many of you might have realized that using discriminant analysis we actually categorize people which is very similar to the clustering analysis of clustering people/objects with similar patterns into one group and thus which could be useful in targeting/segmentation.

but as i said above clustering is only similar to discriminant analysis. Basic difference between the two analysis is that in discriminant analysis, to classify the objects into two similar groups, one has to know the membership for the case that is used to find the classification rule whereas in clustering analysis one cannot know who belongs to which group. In fact sometimes one cannot even know the number of groups to determine the similarities.

For example, if you are interested in determining the difference between several high tolerance free machines using discriminant analysis, cases with known diagnoses of non tolerant machines must be available. and thus based on these known cases, we derive a rule for classifying non tolerance machines.

hope the above information would be useful in determining the basic difference between clustering analysis and discriminant analysis.

Thank you

Source : http://www.norusis.com/pdf/SPC_v13.pdf