根據Rep IV的手冊說明，此統計方法是以構念集合為兩座標軸，將方格資料繪製在二維空間中。方格資料經過主成份分析(principle components analysis)處理，將不同的元素儘可能的分散在二維向量的點圖中。
The grid has been treated as if the elements were points plotted in an n-dimensional space defined by the constructs as axes centered on the means of the elements. The data has then been rotated through principal components analysis to spread the elements out as much as possible in a 2-dimensional plot. Slater (1976; 1977) is the definitive work on such analysis of grids. Joliffe (1986) is a good general source on principal components analysis. Gower (1966) is the definitive work on the spatial model involved, and Gower and Hand (1995) on the presentation of the analysis as a biplot.