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6.3 OUR APPROACH         159




               For this study, we used k-fold cross validation to evaluate our learning models. In this method, the
               dataset is divided into k-fold and the model is repeated k times where in each repetition one fold is
               used to test and the rest is used for training the model. We calculate the mean of this k performance
               and present it in the results.





               6.3.4 EXPERIMENTAL RESULTS
               The adopted classifiers mainly arranged the datasets into two cognitive states and it followed two as-
               sumptions: whether there is sufficient information to classify the cognitive states and if the machine
               learning approach can effectively study the spatial-temporal patterns for classifying the states. Exper-
               imental results were shown and explained. The sequence of data in the form of images belonging to
               every group as depicted in Fig. 6.2 in PS and SP can be comprised as follows:
                                                              PS
                                                PS
                                                   PS
                                                           PS
                                           PS : I ,I ,…,I PS  ,I ,I ,…,I PS                  (6.9)
                                                p1  p2  p16  S1  S2  S16
                                                SP
                                                   SP
                                                           SP
                                                              SP
                                                                   SP
                                           SP : I ,I ,…,I SP  ,I ,I ,…,I p16                (6.10)
                                                        s16
                                                           p1
                                                   s2
                                                s1
                                                              p2
               To generate the data for class P, grouping of both PS and SP trials was necessary.
                  The entire sample for each class was 45. Here the 2D matrix comprised of 80 rows and 16 columns,
               where each column represented a dissimilar snapshot. Here the subject mainly represented the number
               of voxels of dissimilar types. In Table 6.1, the first row represents subjects and the second row repre-
               sents corresponding number of voxels for that subject.
                                                   SP SP
                                                  I , I , ¼ , I  SP     Trial 1
                                                  s1  s2    s16
                                   Class S                                 ¼
                                                         ¼
                                                                        Trial 40
                                                   PS PS
                                                            PS
                                                  I , I , ¼ , I s16
                                                     s2
                                                  s1
                                                   SP SP
                                                  I , I , ¼ , I SP      Trial 1
                                                  p1
                                                            p16
                                                     p2
                                                                           ¼
                                   Class P
                                                         ¼
                                                                        Trial 40
                                                   PS PS    PS
                                                  I , I , ¼ , I p16
                                                     p2
                                                  p1
               FIG. 6.2
               Overall statistics for a specified subject matter.
                Table 6.1 The Number of Voxels in Each Subject
                Subject          04799       04820      04847       05675       05680       05710
                No. of voxels    4949        5015       4698        5135        5062        4634
   161   162   163   164   165   166   167   168   169   170   171