使用情節對經驗法則評估法之應用成效

Abstract

在介面開發中, 選用適合的評估技術對產品開發及產品可用性影響很 大. 由文獻中獲知, 經驗法則評估法是一個快速, 經濟, 效果不錯的評估 技術(Nielsen和Molich,1990); Jeffries,1991), 尤其在成本, 時間 限制之下, 更能發揮其特色. 但其執行與成效上卻有些限制: (1) 需要數 位評估專家參與評估, 始能發揮其評估效用(Nielsen,1994), (2) 它對 真實情境使用者問題的預測能力不高(Cuomo和Bowen, 1994). 因此, 如何 克服限制以提昇經驗法則評估法之成效是一重要議題. 推究預測能力不高的原因, 是由於評估者缺少系統介面應用的相關領域知 識所導致. 所以, 本人預期使用情節的提供可引導評估者提昇評估的問題 層次, 拓廣評估範圍且增加對問題的預測能力, 彌補評估者在系統應用領 域知識之不足及提昇經驗法則評估效用. 研究結果發現使用情節的 提供的確能使評估者拓展問題範圍, 將評估重點由互動層次提昇至語意層 次, 並發現較多與嚴重的語意問題, 且增加評估者對真實使用性問題的預 測能力. 而提供情節的非評估專家在語意, 語法問題的數目與嚴重程度和 無提供情節的評估專家沒有顯著差異, 但與提供使用情節的專家仍有一段 差距, 所以在專家難求或不足的情況下, 提供使用情節予以非專家, 可頂 替專家評估並減少對專家的需求. The effectiveness of usability inspection methods is critical to usabilityevaluation. Previous studies showed that heuristic evaluation was rather effective, compared to other inspection methods. By employing heuristic evaluation,more severe usability problem can be found in a short time periods.However, the application of heuristic evaluation has two limitations: (1) it requires several expert evaluators to evaluation the interface, and (2) the prediction of the real world problems is low. The problem of the low prediction is due to the fact that the evaluators are often lack of the application domain-specific system knowledge. This problem can be remedied by supplying a usage scenario to the evaluators. The purpose of this study was todetermine the effectiveness of a usage scenario on heuristic evaluation. Results showed that the evaluators given a scenario discovered more problems, broadened the scope of problem identification from interaction levelto semantic level, discovered more serious semantic problems, and enhanced theprediction of the real world problems. In addition, it was found that the nonexperts with a usage scenario could perform at the same level. the experts without a scenario. Therefore,it concluded that a scenario can enhance the effectiveness of heuristic evaluation.