4. The method of claim 1, comprising the step of: forming said plurality of clusters by successively splitting the items, based on said skill classifications, into increasingly homogeneous subsets and defining each said subset to be a node.
4. The method of claim 1, comprising the step of: forming said plurality of clusters by successively splitting the items, based on said skill classifications, into increasingly homogeneous subsets and defining each said subset to be a node. 6. The method of claim 4, comprising the further step of: forming a plurality of terminal nodes, wherein each said terminal node contains a unique subset of said items, wherein said plurality of terminal nodes is formed by grouping said items to minimize deviance among items within each said terminal node and maximize deviance among items from different terminal nodes.