Monday 09/07/2007

After a fustrating day yesterday because Window Vista doesn't seem to let neuralworks write the results files out, I reverted to using Windows XP on a different PC. I tested a 32 Input layer, 15 hidden layer and 2 output layer MLP with the full 285 patients after training the network. I then adjusted the score tool threshold to find an optimum but this wasn't as simple as I thought. As the threshold was raised generally the network performed more poorly and this was reflected in the statistical analysis and the overall score. However when the threshold reached 0.9 though by most measures of performance the network performed more poorly the positive predictive value of the network improved. I checked the calculation of this value but it looks correct so I can only assume that it is probably a statistical anomaly. I may test the score tool threshold further with different network configurations but