口碑 (Word-of-Mouth, WOM)，一直被視為是最具影響力的訊息來源之一，其擁有非常可怕又強烈的力量，人人都知道，但沒有一個人真的了解 (吳書榆 2006)。隨著網際網路的興起與普及，人們開始透過網路來汲取新知、蒐集資料或是與其他網友進行交談溝通，也造就了另一種口碑形式—電子口碑 (Electronic Word-of-Mouth, EWOM)。
網路的特性與力量—多向、非同步、匿名性以及多元化的傳播平台與傳播內容—使得電子口碑產生出與以往實體口碑截然不同的傳播、擴散方式，不僅改變了人類傳播訊息之行為模式，也使得電子口碑的相關議題日益受到重視。
為瞭解人們在線上社群中張貼訊息的原因，本研究嘗試以電子口碑內容 (Content) 與涉入程度 (Involvement) 的觀點切入，以問卷自評的方式進行衡量；此外，藉由網路文字的保存性，本研究得以實際觀察網友過去在社群中張貼之文章數量，以瞭解其真實存在之電子口碑傳播行為，作為應變數的衡量依據。
研究結果發現，電子口碑訊息內容的更新性、充分性以及產品涉入程度等因素，的確會對電子口碑傳播行為造成顯著的影響力。亦即，當訊息內容的更新性較高、充分性較低或是產品涉入程度較高時，網友的電子口碑傳播行為也就會越頻繁。
根據研究結果，本研究建議，社群經營者在瞭解網友張貼文章之原因後，便能以此為激勵因子，鼓勵人們踴躍地在討論區內張貼文章、發表言論，以匯聚人氣。若是能因此成功地吸引更多人來造訪此網站，其所帶來之廣告效益也就隨之越大。此外，本研究結合自評（問卷法）與他評（觀察法）兩種方式進行資料蒐集，不僅能改善過去以意圖 (Intention) 推估行為 (Behavior) 的研究方法，同時能避免同方法偏誤 (Common Method Bias) 的問題發生。如此以實際行為為分析依據的研究設計，大幅改善過去傳統口碑行為不易衡量的情況，為本研究的重要貢獻之一。

Word-of-Mouth (WOM), which has a very strong and terrible force, has always been considered as the most influential source of information. Everyone knows that, but no one could really understand it (吳書榆 2006). Through the Internet, people could not only learn new knowledge, collect information, but also communicate with netizens more easily. The rise and popularization of the Internet also creates another form of Word-of-Mouth: the Electronic Word-of-Mouth (EWOM).
The characteristics of the Internet, such as single-and-multi way, anonymity, and synchronicity-and-asynchronicity, as well as various communication platforms and contents, make EWOM generate different ways to spread messages. The emergence of the Internet not only changes the way people disseminate messages, but also makes EWOM related topics received increasing attention.
The main purpose of this study is to understand the reasons why people posted online messages in online community. Through literature reviews, this study regards the content of EWOM and the degree of involvement as potential reasons of postings, and creates 6 independent variables to analyze. Moreover, the online texts keep netizens’ actual posting behaviors, so that we could count exactly the number of each netizen’s posting as a dependent variable.
The results show that the currentness and sufficiency of the EWOM content, as well as the product involvement, will cause significant influence to EWOM communication behavior. That is, when the EWOM content is more current and more sufficient, or people have higher product involvement, the netizens will tend to disseminate EWOM messages more frequently.
Based on the findings, the operators in the online community could use currentness and sufficiency of EWOM content as well as product involvement as motivating factors to encourage people post messages or discuss more actively. If they could successfully attract more and more people to visit the sites, crowds would bring a result of the greater advertising effectiveness. In addition, this study combines questionnaire and observation methods to collect data could efficiently avoid common method bias. Moreover, using actual posting numbers as netizens’ posting behaviors improves the situation that former researchers use people’s intentions to estimate their behaviors. To sum up, using actual behavior as an analyzing factor is a better way to measure the effect of WOM, and it is also one of the important contributions of this study.

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