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Preceived Usefulness, Preceived Ease of Use, and User Acceptance of Information Technology

Preceived Usefulness, Preceived Ease of Use, and User Acceptance of Information Technology. 報告人 : 徐而柔 張春秀 2010/5/1. Agenda. 研究動機 研究理論 研究方法 Significant findings Research implications. 研究動機. 建立一套有效的量表來衡量電腦使用習慣 (computer usage) 。 本研究目的是發展並驗證兩個明確的假設變數，此兩變數是 computer usage 的決定因子。 兩變數 :

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Preceived Usefulness, Preceived Ease of Use, and User Acceptance of Information Technology

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  1. Preceived Usefulness, Preceived Ease of Use, and User Acceptance of Information Technology 報告人:徐而柔 張春秀 2010/5/1

  2. Agenda • 研究動機 • 研究理論 • 研究方法 • Significant findings • Research implications

  3. 研究動機 • 建立一套有效的量表來衡量電腦使用習慣(computer usage)。 • 本研究目的是發展並驗證兩個明確的假設變數，此兩變數是computer usage的決定因子。 • 兩變數: • 認知有效性(perceived usefulness) • 認知使用容易性(preceived ease of use)

  4. Perceived Usefulness & Perceived Ease of Use • Perceived usefulness: The degree to which a person believes that using a particular system would enhance his or her job performance. 個人相信使用某一種資訊科技將可增加工作表現的程度。 • Perceived ease of use: the degree to which a person believes that using a particular system would be free of effort. 個人相信使用某一種資訊科技將能免除其努力（free of effort）的程度

  5. Theoretical FoundationsExpectancy theory • A matrix-oriented measurement procedure was used to produce an over all index of ‘motivational force’ that combined these three constructs. 矩陣導向衡量程序已有一個全面性的Motivational force的指標，此指標與本研究的三構面有相關。

  6. Theoretical Foundations Self-efficacy theory • Bandura’s (1982)做了許多有關self-efficacy(自我勝任感)的研究，將self-efficacy定義為評估個人採取必要的行動去處理預期處境的程度。 • Self-efficacy的定義相似於perceived ease of use。 • Self-efficacy的信念在理論上的功能可視為影響行為的接近決定因子(proximal determinants of behavior)。

  7. Theoretical Foundations-Behavioral decision theory: Cost-benefit paradigm • cost-benefit paradigm(成本-效益模型)是由行為決策理論中而來的，與perceived usefulness and ease of use有關聯。 • 這個方法有效的解釋為什麼決策者改變其抉擇策略以反應作業的複雜度(task complexity)。 • 近來的工作開始採用相同的分析格式，已成為資訊效能展示的樣式(the effectiveness of information display formats)。

  8. Theoretical Foundations Adoption of innovations • Tornatzky and Klein(1982) 發現 compatibility(相容性), relative advantages(相關優勢), and complexity(複雜性) 三者有一致性重要相關於創新類型 (innovation types). • Complexity 相當接近於perceived ease of use的定義。

  9. Theoretical Foundations Evaluation of information reports • 過去MIS的評估資訊發佈(evaluation of information reports)之研究，回應到本研究的兩項變數usefulness and ease of use. • Larcker and Lessig(1980)發現兩個distinct factors: perceived importance(認知重要性) and perceive usableness(認知可用性). • 這兩項因子分別相似於本研究的perceived usefulness and perceived ease of use.

  10. Theoretical Foundations Channel disposition model • Swanson(1982, 1987) 的channel disposition model，解釋抉擇與資訊公佈使用( the choice and use of information reports)的因子，有二部分: 1.資訊品質屬性(attributed information quality) to measure information quality 2.易接近屬性(attributed access quality to measure and access quality. • Accessibility corresponds to perceived ease of use as defined above. • Information quality of value parallels perceived usefulness. • A close correspondence to perceived usefulness and ease of use. • Self-reported(自我陳述) information channel use correlated with the value dimension(價值量度) and accessibility dimension(易接近性量度).

  11. Theoretical Foundations -Marking • Hauser and Simmie (1981)關注在溝通科技對於使用者認知的影響，有兩項因子: ease of use and effectiveness，其中 effectiveness相似於 the perceived usefulness. • Ease of use and effectiveness 這兩項因子均影響user preference 的構成。

  12. Theoretical Foundations-Human-computer interaction (HCI) • HCI 研究著重在ease of use的設計. 大部分的研究專注在客觀性量測(objective measures of ease of use). • 雖然在給定的系統使用下，客觀性量測(objective measures of ease of use)明確地與使用者成效有關，但是主觀性ease of use 會更有影響力，影響使用者的決策是否使用此系統，這論點與主觀性量測不相同。

  13. Convergence of findings From multiple disciplinary vantage points, perceived usefulness and perceived ease of use are indicated as fundamental and distinct constructs that are influential in decisions to use in formation technology.

  14. 研究方法 Scale Development & Pretest Study 1 Study 2 14

  15. 量表的發展 PU & PEOU根據上述各項理論，產生各14個candidate items. 若達到0.8以上的信度，建議每個構念使用10個items (Davis, 1986) 15

  16. Initial Scale Items for Perceived Usefulness 1. My job would be difficult to perform without electronic mail. 2. Using electronic mail gives me greater control over my work. 3. Using electronic mail improves my job performance. 4. The electronic mail system addresses my job-related needs, 5. Using electronic mail saves me time. 6. Electronic mail enables me to accomplish tasks more quickly. 7. Electronic mail supports critical aspects of my job. 8. Using electronic mail allows me to accomplish more work than would otherwise be possible. 9. Using electronic mail reduces the time I spend on unproductive activities. 10. Using electronic mail enhances my effectiveness on the job. 11. Using electronic mail improves the quality of the work I do. 12. Using electronic mail increases my productivity. 13. Using electronic mail makes it easier to do my job. 14. Overall, I find the electronic mail system useful in my job. 16

  17. Initial Scale Items for Perceived Ease of Use 1. I often become confused when I use the electronic mail system. 2. I make errors frequently when using electronic mail. 3. Interacting with the electronic mail system is often frustrating. 4. I need to consult the user manual often when using electronic mail. 5. Interacting with the electronic mail system requires a lot of my mental effort. 6. I find it easy to recover from errors encountered while using electronic mail. 7. The electronic mail system is rigid and inflexible to interact with. 8. I find it easy to get the electronic mail system to do what I want it to do. 9. The electronic mail system often behaves in unexpected ways. 10. I find it cumbersome to use the electronic mail system. 11. My interaction with the electronic mail system is easy for me to understand. 12. It is easy for me to remember how to perform tasks using the electronic mail system, 13. The electronic mail system provides helpful guidance in performing tasks. 14. Overall, I find the electronic mail system easy to use. 17

  18. Pretest • Sloan School of Management, MIT 15 名電腦使用者進行排序與分類的工作 • 利用pretest將問項刪減至10項，以提高內容效度。 • 判斷準則： • 排序 - 每一item符合構念定義之程度 • 分類 - 定義較相似之問項分為一類，3~5類 18

  19. 認知有用性 PU Pretest Cluster A: 工作效率 Cluster B: 生產力與節省時間 Cluster C: 系統對工作的重要性 19

  20. 認知易用性 PEOU Pretest Read Clear & Understandable Cluster A: physical effort Cluster B: mental effort Cluster C:系統學習上的難易度 20

  21. Study 1 • 目的：針對10 個itmes來分析信度、聚合效度、區別效度與因素效度。 • 研究樣本數 : • 120 users IBM Toronto Development Lab. • 6個月研究經驗 • 樣本回覆率：93%, 112人 • 問卷：自陳式7度量表 • 測試系統: • PROFS electronic mail system (brief messaging facility) • XEDIT file editor (command-driven edition capabilities) 21

  22. 信度 Cronbach α Study 1 22

  23. 效度 Study 1 檢驗效度方法：構念效度 檢驗技術：多元特質多重方法矩陣法（multitrait-multimethod, MTMM; Campbell & Fiske,1959) 23

  24. MTMM分析總表 Study 1 MTHM 次高相關 MTHM 次高相關 HTMM 低度相關 HTHM 最低相關 HTMM 低度相關 HTHM 最低相關 24

  25. 效度 Study 1 • 聚合效度=>Support! • PU：90 個MTHM相關係數達顯著 • PEOU：86個(95.65%) MTHM相關係數達顯著 • 區別效度=>Support! • PU: 1,800 comparisons were confirmed without exception. • PEOU: 1,800 comparisons中，有58個例外 (3%) • HTHM的相關係數並未明顯高於HTMM 25

  26. 因素效度 Study 1 分析方法：主成分分析&斜交轉軸 分析目的：PU&PEOU分別為獨立的兩個構念 26

  27. Scale Refinement Study 1 • 依據斯布校正公式 (Spearman-Brown Prophecy formula)，保留6個可達到0.9的信度的問項作為第二次研究的問項修正沿用。 • PEOU Scale Items: • 同源偏差(CMV)，將5 個負面問項刪除，並修改成為6個問項。 • 量表題項修正法(scale item trimming) • PU Scale Items: • 採用項目分析(Item Analysis)，針對10個問項進行item-total相關係數之Z檢定以提高信度，其中#3, 5, 6, 8, 9, 10係排名較高的項目=>選擇6個問項來代表量測 27

  28. Study 2 • 近似於 prototype testing應用或是 system selection狀況 • 對象：Boston大學40位MBA夜間部學生。 • 問卷：自陳式7度量表 • 測試軟體： • Chart-Master: menu-driven package • Pendraw: bit-mapped graphics (點陣圖影像); using digitizer tablet and electronic pen • 提供參與測試者1小時的軟體使用體驗 28

  29. 信度 Study 2 • Cronbach α • PU=.98 • PEOU=.94 29

  30. 效度 Study 2 聚合效度=>Support! (2/72相關係數不顯著) 因素效度=> Support!(主成份分析法、斜交轉軸法) 30

  31. 使用程度的關係 Study 2 n.s n.s n.s n.s PU使用程度間的相關係數 顯著大於 PEOU使用程度間的相關係數。 31

  32. 使用程度的關係 Study 2 • 迴歸分析結果： • PEOU不變的情況下，PU對使用程度有顯著的影響。 • PU不變的情況下，PEOU對使用程度卻無顯著性的影響。 • 有多元共線性Multicollinearity發生，預測變項彼此重疊很低(.07)，且共變異數與估計項目參數 很低(-.004), 可忽略。 • Regression and Partial correlation = >PEOU PU usage 32

  33. Summary for Method • 本研究係針對影響電腦使用的兩項重要構面，發展及驗證新量表： • 由文獻回顧定義PU及PEOU，說明PU及PEOU 與相關系統使用(程度)之因果關係，並研擬初始量表(每一構面各14個問項)。 • 經Pretest將每一構面刪減至10個問項。 • 透過Study 1將每一構面刪減至6個問項。 • 以Study 2驗證信度及效度。

  34. Significant findings • Usefulness was significantly more strongly linked to usage than was ease of use. • From a causal perspective, the results are consistent with an ease of use  usefulness usage chain of causality(因果關係). • Goodwin(1987) 對於因果流程提出不同看法: 一個系統有效的功能性是依賴其可用性(the effective functionality of a system depends on its usability). • 本研究的因果關係解釋是初步的，應該再做更深入的實驗。If true, however, it underscores the theoretical importance of perceived usefulness.

  35. Research implications • The usage measures employed were self-reported as opposed to objectively measured. Not enough is currently known about how accurately self-reports reflect actual behavior. • Also since usage was reported on the same questionnaire used to measure usefulness and ease of use, the possibility of a halo effect should not be overlooked. • Future research addressing the relationship between these constructs and objectively measured use is needed before claims about the behavioral productiveness can made conclusively.

  36. The End

  37. Appendix 37

  38. MTMM • 多元特質多重方法矩陣法(Multitrait - multimethod matrix，MTMM) • MTMM：monotrait –monomethod 單一特質-單一方法 • MTHM：monotrait –heteromethod 單一特質-多重方法 • HTMM：heterotrait –monomethod 多元特質-單一方法 • HTHM：heterotrait –heteromethod 多元特質-多重方法 38

  39. TAM Model 39

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