This observation indicates that we should be able to improve the answer accuracy of the QA system by optimizing the LL of the filter model in isolation, similar to how, in automatic speech recognition, the LL of the language model can be optimized in isolation to improve the speech recognition accuracy (Huang et al., 2001).
in some cases both who and where q-a pairs occurred in the same cluster, so as to better answer questions like Who won the World Cup?, where the answer could be a country name.