口碑是非常有效的行銷工具，但是實際上並非完全有效，在某些情境下，消費者即使收到正面口碑仍然不願意購買，而本研究將此定義為「正面口碑失效」。本研究以Sweeney, Soutar, and Mazzarol（2008）影響口碑有效性的四大構面為基礎，回顧過去正面口碑影響因素，並利用量化及質化兩階段進行研究，其中，第一階段量化研究採用封閉式問卷輔以開放性題項，瞭解正面口碑失效現象之普遍性及可能因素，第二階段則利用個人深度訪談之關鍵事件法調查正面口碑失效因素對消費者決策流程之影響。本研究結果發現6個正面口碑失效構面，分別為：個人構面、人際間構面、訊息構面、情境構面、心理構面與不適配構面，共包含19個因素，且正面口碑失效因素在消費者不同決策階段（注意、興趣、搜尋和購買）影響不同。
本研究之貢獻為發現過去由正面口碑有效觀點無法發現之正面口碑失效因素，並應用De Bruyn and Lilien（2008）多階段概念彌補過去正面口碑影響之相關研究多僅探究單一階段的可能缺失，藉由瞭解正面口碑失效現象，更能真正認識口碑。實務上，行銷活動在消費決策階段扮演不同角色及目的，例如：形成接收者認知和實際購買等。藉由了解不同階段的正面口碑失效因素，有助於提升正面口碑的影響力，最後，本研究有助警惕企業進行口碑行銷時，在某些情況下不應過度依賴正面口碑效果，而耗費行銷資源。

Word-of-mouth (WOM) is a highly effective marketing tool; however, it is not entirely effective. In certain cases, despite receiving positive WOM, consumers will not purchase. We define positive WOM that cannot achieve expected results as Positive WOM Ineffectiveness. This paper reviews from four factors in Sweeney, Soutar, and Mazzarol (2008) and conducts the quantitative and qualitative study. The quantitative study is to understand universality of positive WOM ineffectiveness and its factors by a questionnaire consisting of closed-ended questions and an open-ended question. The qualitative study is to present positive WOM ineffectiveness factors on decision-making process by Critical Incident Technique. We discovered 19 reasons for positive WOM ineffectiveness, which was summarized into 6 factors: personal factors, interpersonal factors, message factors, situational factors, psychological factors, and unfit factors. We also found that different factors of positive WOM ineffectiveness have varying effects on the decision-making process.
The value of this paper is to discover the ineffectiveness factors that cannot be discerned from effectiveness perspectives. In addition, we applied the multistage model of WOM influence provided by De Bruyn and Lilien (2008) onto positive WOM ineffectiveness to enhance our understanding of the WOM field. In practice, the purpose of marketing plans varies depending on the different decision-making process scope, some are to enhance consumer perception, and others might intend to trigger purchase intentions. Therefore, understanding reasons for positive WOM ineffectiveness at different stages can help enhance WOM effectiveness. We expect to inform companies when not to rely heavily on WOM marketing in specific instances, and not to waste marketing resources.

AISAS: the concept is adopted form Wikipedia, http://ja.wikipedia.org/wiki/AIDMA
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