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. 5. The method of claim 4, wherein said plurality of clusters is formed by selecting a locally optimal sequence of splits using a recursive partitioning algorithm to evaluate all possible splits of all possible skill classification variables at each stage of the analysis.