I am using the fitting app in Matlab ANN (nnstart), but I am confused about the R value figure generated by the tool after traing. What is the Horizontal axis represent in R value figure in the ANN fitting? For example, the attached figure is R value of a ''body fat'' training example. Why the x-axis range is 0-40 or 0-50? It is not the sample number? How does the x-axis (Target) is obtained? Could anyone help me? Thanks.
The plot shown is created using plotregression function. It shows relation between the targets on the y axis, and the predicted output on the y axis. the axis limits are based on the limits of these two values. See the following code for example.