「無力感」此護理診斷是臨床上既普遍又重要的健康問題，但是常被護理人員所忽略，而且國內外的相關性研究也較少有系統性的探討，無法提供明確的指引。因此希望藉由本研究對無力感定義性特徵的臨床效度測定，找出最具代表性及具體性的定義性特徵。本研究為描述性研究，針對62位鬱血性心衰竭病患，以研究者所訂立之「無力感定義性特徵評量表」，經由觀察、會談、測量及查閱病歷等方式收集資料，並應用SPSS 9.0 for windows軟體中的描述性統計、推論性統計、信效度及因素分析等方法。二十項定義性特徵在刪除5項不重要的定義性特徵後，剩下十五項定義性特徵的Cronbach's Alpha值為 .87，矯正之單項 / 總項相關係數大多大於.40以上，顯示其為具有相當信度的評量表。因素分析後共選取三個次概念「不適應」、「不滿意」和「不關心」來涵蓋。依據特徵值、因素負荷量、中數值、矯正的單項 / 總項的相關係數及去除此項之Alpha係數等五項基本條件，選出十項必要定義性特徵，Cronbach's Alpha值為 .86。總括而言此次研究結果：（1）十五項定義性特徵具有同質性。（2）因素分析後共選取三個次概念來涵蓋。（3）十項必要性定義性特徵，具有肯定的內在一致性，實可為評估之依據。

　　　　　“Powerlessness” is a common and serious health problem in diverse clinical settings, especially in chronic illness. The purpose of the study were to indentify the essential defining characteristics of “powerlessness” and establish the reliability and construct validity for it. An evaluation questionnaire for defining characteristics of “powerlessness” was designed to interview 62 congestive heart failure patients. Clinical assessment was carried out by observation, measurement, semi-structure interview and patient's chart. Results of the study showed that the 15 defining characteristics have a high coefficient alpha ( .87) and a significant average inter-item correlation ( .18). Construct validity of the total scale of 15 items was represented by factor analysis. The three factors describing the subconcepts of “powerlessness” were labeled as “inadaptation”, “malcontent”, and “incuriosity”. The reliability and construct validity were acceptable. The study concluded that the established 15 defining characteristics were homogeneous for “powerlessness”, three subconcepts of defining characteristics were able to be indentified, and the identified 10 essential defining characteristics were homogeneous and could be a reliable instrument for prompt diagnosis of “powerlessness”.