Unni Cathrine Eiken February 2005

Unni Cathrine Eiken February 2005 Unni Cathrine Eiken February 2005

10.04.2013 Views

The aim of the tests performed in this section was to see if the accuracy of the classifier could be enhanced by training on a complete context pattern with the appropriate concept group as category label. Test 1 Training set: EPAS_arg1 with no pronouns and concept classes as category label, argument 1 ignored. Test method: leave-one-out Result: 56,54% (108/191) In this test, the classifier was trained on two features of the EPAS, ignoring argument 1. This test is analogous to test 2 in section 4.1.2.1, which had an accuracy of 41,20% correct classifications. In addition to the 108 correctly classified instances, additional five instances were assigned categories which are semantically similar to the correct category. This was true for Kripos-spesialist (Kripos specialist), politimester (chief of police), medarbeider (co-worker) and polititjenestefolk (police workers), which were all assigned the category POLICE. These words are not part of the concept group POLICE, but are obviously semantically related to the members of this concept group. Had these words occurred more frequently in the data material, they could have been expected to show a distribution allowing for their inclusion in POLICE. The results of this test suggest that labeling EPAS with concept group labels heightens the accuracy of the classifier. This is not surprising, given the fact that a higher number of context patterns/EPAS are labeled with the same category in such an approach, making the generalisable material larger. Test 2 Training set: EPAS_arg1 with no pronouns and concept classes as category label. Test method: leave-one-out Result: 86,91% (166/191) This test was performed to see if training the classifier on the entire structure of an EPAS increases the accuracy of assigning concept labels to the structures. The classifier was trained on all three features of the EPAS. In this case, the classifier performed with a fairly high accuracy, assigning the correct category in 166 of 191 cases. It is obviously an advantage that all parts of 76

the EPAS can be used in the classification phase when the category to be assigned is not literally a part of the structures to be learnt from. Test 3 Training set: EPAS_arg1 with no pronouns and concept classes as category label, argument 1 ignored. Test set: EPAS_arg1 with pronouns and concept classes as category label Result: 76,92% (20/26) As was the case in the corresponding test in section 4.1.2.1, two of the wrongly assigned categories were in fact within the same semantic group as the correct category. Regarding these as correct assignments would heighten the result to 84,61%. As was the case in the previous two tests, the assigned categories in these cases are too infrequent in the EPAS list to surface in the associated concept groups. Test 4 Training set: EPAS_arg2 with no pronouns and concept classes as category label, argument 2 ignored. Test set: EPAS_arg2 with pronouns and concept classes as category label Result: 83,33% (5/6) When training the classifier on the EPAS_arg2 list using concept class labels as categories and testing on the set of EPAS with pronouns in argument 2 position, the classifier resolved five of the six test instances correctly. In the corresponding test in section 4.1.2, the classifier did not assign the correct category in any of the six test cases. We did, however, see that five of the test instances were assigned categories which were semantically similar to the correct antecedent. In view of the results in the initial test, it came as no surprise that the classifier performed so much better when used in connection with the concept class labels. 77

The aim of the tests performed in this section was to see if the accuracy of the classifier could be<br />

enhanced by training on a complete context pattern with the appropriate concept group as<br />

category label.<br />

Test 1<br />

Training set: EPAS_arg1 with no pronouns and concept classes as category label, argument 1<br />

ignored.<br />

Test method: leave-one-out<br />

Result: 56,54% (108/191)<br />

In this test, the classifier was trained on two features of the EPAS, ignoring argument 1. This<br />

test is analogous to test 2 in section 4.1.2.1, which had an accuracy of 41,20% correct<br />

classifications. In addition to the 108 correctly classified instances, additional five instances<br />

were assigned categories which are semantically similar to the correct category. This was true<br />

for Kripos-spesialist (Kripos specialist), politimester (chief of police), medarbeider (co-worker)<br />

and polititjenestefolk (police workers), which were all assigned the category POLICE. These<br />

words are not part of the concept group POLICE, but are obviously semantically related to the<br />

members of this concept group. Had these words occurred more frequently in the data material,<br />

they could have been expected to show a distribution allowing for their inclusion in POLICE.<br />

The results of this test suggest that labeling EPAS with concept group labels heightens the<br />

accuracy of the classifier. This is not surprising, given the fact that a higher number of context<br />

patterns/EPAS are labeled with the same category in such an approach, making the generalisable<br />

material larger.<br />

Test 2<br />

Training set: EPAS_arg1 with no pronouns and concept classes as category label.<br />

Test method: leave-one-out<br />

Result: 86,91% (166/191)<br />

This test was performed to see if training the classifier on the entire structure of an EPAS<br />

increases the accuracy of assigning concept labels to the structures. The classifier was trained on<br />

all three features of the EPAS. In this case, the classifier performed with a fairly high accuracy,<br />

assigning the correct category in 166 of 191 cases. It is obviously an advantage that all parts of<br />

76

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