以最大影響策略之主動學習法改進基於概念網之情緒辭典

情緒分析旨在分析一段自然語言文字中所隱含的情緒。為了找出文字中的情緒，許多情緒分析的研究仰賴情緒辭典查詢文字片段中隱含的情緒值，並據此總結出整段文字的情緒。在先前的研究中，我們提出了一個以 ConceptNet 為基礎的半監督式方法，將情緒值從已知情緒值的概念（concept）傳遞到其它的概念上，並建立一個具有情緒數值的概念層級情緒辭典。然而，由於已知情緒值的概念仍不足以在這個巨大的圖中傳遞情緒值。並且，收集大量情緒標註也相當耗費成本。在這個研究，我們藉由加入一個主動式學習元件來改良我們先前的方法。原有的數值傳遞方法被略微修改，以估計每個概念情緒值的不確定性分數。基於這些不確定性分數，我們提出「最不確定」與「最大影響」這兩個查詢策略（query strategy）以選擇需要情緒標註的概念。實驗結果顯示，我們提出的不確定性估算方式能夠合理地區分確定的概念與不確定的概念。並且，「最不確定」與「最大影響」兩者皆優於「隨機選取」策略。此外，「最大影響」能夠降低比「最不確定」策略更多的錯誤，原因在於其同時考慮了概念的不確定性與影響力。我們證實了我們提出的主動式學習元件確實能夠改進現有情緒辭典的品質。

關鍵字

情緒辭典；數值傳遞；主動學習；群眾外包

並列摘要

Sentiment analysis aims to analyze the sentiments behind natural language text. Most sentiment analysis methods rely on sentiment dictionaries to identify sentiments in text. Our previous work proposed a ConceptNet-based semi-supervised approach, which propagated sentiment values from seed concepts to other concepts in ConceptNet. However, the seed concepts are insufficient to propagate sentiment values in a larger graph, and collecting large numbers of annotated seed concepts can be expensive. In this work, we refine our previous method by adding an active learning component. We also modify our previous value propagation method to estimate certainty score for each concept's sentiment value. Based on these certainty scores, two query strategies, maximal uncertainty (MU) and maximal impact (MI), are proposed for choosing which concepts to send for sentiment annotation. Our experiment shows that our proposed certainty estimation methods can discriminate certain concepts from uncertain ones. Also, we show that both MU and MI strategies outperform the ``random' strategy. Furthermore, MI corrects more concepts than MU, since it considers both uncertainty and influence of concepts. We conclude that our proposed active learning component can improve the quality of existing sentiment dictionaries.

並列關鍵字

Sentiment Dictionary ； Value Propagation ； Active Learning ； Crowdsourcing

參考文獻

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以最大影響策略之主動學習法改進基於概念網之情緒辭典

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