1. A computer implemented method for identifying manufacturing events significant to a value of a given target production quality in semiconductor fabrication, comprising: storing in a storage unit in communication with a processor a manufacturing history record for each item of a group of items in a semiconductor fabrication process, each manufacturing history record having a unique item identifier, a target value representing a measured value of a given target, and a manufacturing event vector representing a plurality of different manufacturing events and whether or not each of the manufacturing events occurred in the manufacturing of the item; wherein each of said plurality of manufacturing events is represented as a step-tool pair representing at least one of a particular manufacturing step and a particular manufacturing equipment used in said semiconductor manufacturing process, and wherein said manufacturing event vector for each item includes a plurality of said step-tool pair attributes, each attribute having a value representing whether or not the step-tool pair was applied in the manufacturing of the item; generating, using said processor, a binary decision rule, the binary decision rule being in a form IF/THEN/ELSE, said generating including selecting a pattern of manufacturing events such that an in-pattern statistic differs by at least a given significance threshold from a global statistic, the in-pattern statistic being a statistic of the target value for all items of the group having the pattern of manufacturing events in the item's fabrication history record and the global statistic being the same statistic of the target value for all items of said group; and using the binary decision rule for improving or taking remedial action with respect to particular tool(s) or recipe(s) used in said plurality of different manufacturing events in said semiconductor manufacturing process.