The analysis of STEP system performance vs. GI-H4 and of the disagreements between manually annotated HM and GI-H4 showed that the greatest challenge with sentiment tagging of words lies at the boundary between sentimentmarked (positive or negative) and sentimentneutral words.
as annotators proceed from the core of the category to its periphery, word mem-bership in this category becomes more ambiguous, and hence, lower inter-annotator agreement can be expected for more peripheral words.