The present invention applies the data mining methodology by which the wafer exposure effectiveness and efficiency are predictable in terms of the chip size, chip length and chip width. More specifically, in the present invention, an index, named “Mask-field-utilization weighted Overall Wafer Effectiveness” (MOWE), integrates the two parameters of “Overall Wafer Effectiveness” (OWE) and “Mask-Field-Utilization” (MFU), mainly regarding the wafer exposure effectiveness and efficiency respectively, in order to construct a model tree of the MOWE to achieve the data mining. By the MOWE model tree, the causal relationship between design independent variables and fabrication dependent variables is constructed, which can be accordingly applied as design guidelines in the design phase to improve the chip layout in order to produce a better wafer exposure effectiveness and efficiency.