產品保證費用係透過模型估計而得，公司會透過變更產品保證決策傳遞未來前景發展之內部資訊，因此產品保證費用對於公司未來盈餘或前景有著不確定性影響，會計資訊之不確定性性質會影響分析師之預測行為，故本文擬探討產品保證對於分析師預測誤差之影響。由於文獻發現公司會使用產品保證費用進行盈餘管理，因此產品保證費用存在內生性問題，本文以兩階段最小平方法（2SLS）解決此問題。以手工蒐集美國產品保證費用較高的四種製造業之上市公司，以其2004年至2008年之資料為樣本，進行實證分析，本研究發現產品保證對於分析師預測誤差有顯著影響，因為產品保證費用具備不確定性性質，當分析師對於高不確定性資訊進行分析時，所面對之資訊複雜度會愈大，因而產生較大預測誤差。但當公司能見度較高時，產品保證費用對於分析師預測誤差之影響會較小。

When a product is sold with a warranty, the company necessarily accrues a warranty expense, which is estimated based on product reliability, product terms, customer usage and the company' projections of future claims etc. Companies deliver their internal information to outsiders through changing policies on product warranty. Therefore, the warranty expense is an implication of an uncertainty about company' future earnings and further influences on analysts' forecast behavior. The purpose of this paper is to examine the influence of product warranties on analysts' forecast behavior. Moreover, the literature shows that if companies tend to manage earnings via warranty expenses, which an endogenous problem is created. We employ two-stage least squares method to solve it. We use US listed companies in four manufacturers with stronger product warranties from 2004 to 2008 as the sample, the empirical result shows a positive significant relationship between abnormal product warranty expense and analysts forecasts errors, which because analysts tend to have larger earnings forecast errors due to the uncertainty and the complexity of the product warranty. However, this paper also finds that the positive relationship is lower for companies with large visibility.