CHAPTER 2 - Biplots in Practice, by Michael Greenacre
Video 2.1
In this video we see the three-dimensional scatterplot of species d versus pollution (y) and depth (x) and the regression plane defined by the model d = 6.135-1.388y+0.148x [see equation (2.1) and the schematic version on the left of Exhibit 2.2].
CHAPTER 2 - Biplots in Practice, by Michael Greenacre
Video 2.2
In this video we see the same three-dimensional scatterplot as above, but with all variables standardized.
The gradient vector and contour lines are shown in red in the plane of the explanatory variables pollution (y) and depth (x)
and the corresponding vector in the regression plane and the heights corresponding to the contour lines are shown in white.