corrcoef - plotregression (which algorithm plotregression use)

Hi,

I want to ask which algorithm does the plotregression use for calculating the R value?

"the R value spotted out above the window after we run the plotregression function (in ANN,or etc..)."

- Is it the R value that is calculated with the function R = corrcoef(X) ? or with a different function.

Best Regards.

Answer 1

[Lucas García]

plotregression actually uses the regression function (also from Neural Network Toolbox) to compute the R value.

However, note that results are almost identical to corrcoef's output.

load simplefit_dataset
net = newff(simplefitInputs,simplefitTargets,10);
[net,tr] = train(net,simplefitInputs,simplefitTargets);
simplefitOutputs = sim(net,simplefitInputs);
plotregression(simplefitTargets,simplefitOutputs);

R value in plotregression is computed this way:

[r,m,b] = regression(simplefitTargets,simplefitOutputs);

Using corrcoef:

c = corrcoef(simplefitTargets,simplefitOutputs);

Values should be almost identical. In my test:

norm(c(1,2) - r)

ans =

       5.551115123125783e-16