Two-way interaction of input variables in the sensitivity analysis of neural network models

摘要

The major shortcoming of artificial neural networks (ANN) is the difficulty of interpreting the knowledge gained by "black-box" type models. Several methods, commonly called sensitivity analysis, have been proposed to overcome this disadvantage. The relative importance of each input variable on the output can then be determined. One of the existing methods uses partial derivatives (PaD) to visualise the contribution of single variables. However, in ecology, relationships are the result of multivariate and non-linear conditions; phenomena are rarely due to a simple cause or to a unique perturbation. For these reasons, a modification of the PaD (PaD2) was implemented to analyse the contribution of all possible pair-wise combinations of input variables, taking into account the two-way interactions between variables.