... the first andsecond factor (independent) variables. 1. The four vertex points are drawn. The vertex points are ( -1, -1) ,( -1, 1), (1, 1), (1, -1) . At each vertex point, the average of all theresponse ... and so we conclude that the X1*X2 term is notsignificant. 1. 3.3 .10 .1. DEX Contour Plothttp://www.itl.nist.gov/div898 /handbook/ eda/section3/eda33a1.htm (3 of 4) [5 /1/ 2006 9:56:35 AM] Importance:AssumptionCheckingAs ... the vertex point (i.e., there iscurvature). 1. 3.3 .10 .1. DEX Contour Plothttp://www.itl.nist.gov/div898 /handbook/ eda/section3/eda33a1.htm (2 of 4) [5 /1/ 2006 9:56:35 AM] Sample PlotThe histogram...