Is it OK to increase validation checks and decrease min gradient while training neural network?

My input vector is a 130*85 matrix and my target vector is 130*26 matrix. I am using the below parameters for training the network with 60 hidden nodes.

       net.trainParam.max_fail = 50;
       net.trainParam.min_grad=1e-10;
       net.trainParam.show=10;
       net.trainParam.lr=0.01;
       net.trainParam.epochs=1000;
       net.trainParam.goal=0.001;`

As you can see I have set the max_fail to 50 and min_grade to 1e-10. While the default values will be 6 and 1e-5 respectively. But with the default values, the training stops early with out reaching the performance goal. By setting these parameters,the training is stopped when the performance goal is reached. So. Is it OK to change these parameters?

Answer 1

[Greg Heath]

The most important objective is to obtain an acceptable ratio of mean-square error to mean-target-variance for RANDOM subsets of NONTRAINING data. I find the best way to do this is to try to find the smallest value of H (No. of hidden layer nodes) that will yield

 mse(ytst-ttst)/var(ttst,1) <= 0.01

i. e., 99% of a random test target subset variance is successfully modeled.

In order to do this I use the default 70/15/15 trn/val/tst data division and the training data goals

 MSEgoal = max( 0, 0.01*(Ntrneq-Nw)*var(ttrn,0)/Ntrneq )
 MinGrad = MSEgoal/100
 net.trainParam.goal     = MSEgoal ;
 net.trainParam.min_grad = MinGrad ;

For an I-H-O node topology obtained from N pairs of I-dimensional inputs and O-dimensional targets

 [ I N ] = size(input) %  [ 85 130 ]
 [ O N ] = size(target)%  [ 26 130 ]

 Ntrn   = N-2*round(0.15*N) %   90 training examples
 Ntrneq = Ntrn*O            % 2340 training equations

 % Nw = (I+1)*H+(H+1)*O       % Number of unknown weights
 % For a robust design desire Ntrneq >> Nw or
 % H << Hub = -1+ceil( (Ntrneq-O) / (I+O+1)) % 20

 Hmax = 20
 dH   = 2
 Hmin = 1
 Ntrials = 10

 Design many nets and choose the best using the validation set performance.

 for h = Hmin:dH:Hmax
  ....
     for i = 1: Ntrials
  ... 
     end
 end

I have posted many, many examples on the NEWSGROUP and ANSWERS, Search on

 greg Ntrials

Hope this helps.

Thank you for formally accepting my answer

Greg

[Hamid Radmard Rahmani]

I think the answer is not relevant to the question.

[Greg Heath]

The question is not relevant to obtaining a good design. The answer is oriented to guide the questioner to more relevant issues.

Answer 2

[papoo]

Thanks Greg, so useful.