The PeP Project: Evaluating the Responsiveness of SAP Applications from a User-Centered Perspective – Appendix

By Gerd Waloszek, SAP User Experience, SAP AG, and Ulrich Kreichgauer, oCTO, SAP AG – October 13, 2009 • original article (story)

This page offers additional information for the article The PeP Project: Evaluating the Responsiveness of SAP Applications from a User-Centered Perspective.

 

Overview of the Aspects of Human Performance at the Computer

Figure 1 below provides a schematic overview of the aspects of human performance at the computer, the primary questions that are involved, and how these aspects are related to technology and UI design:

The Aspects and the Related Questions

  • System performance relates to the question: "How fast is the computer?"
    Optimizing system performance includes all involved technical components, such as the processing, the network, and the visual rendering. Speed is the motto, here, and we are in a purely technical domain. Increasing speed reduces waiting times, and it is hoped that with sufficient speed these can be reduced to practically zero.
  • Human performance relates to the question: "How can we improve human performance through UI design?"
    It points to the fact that user interface design plays a critical role for the performance of human users and attempts to design software applications in ways that the users' performance is optimized. Here, we are primarily in the UI design domain, including interaction, information, and visual design, although technical considerations also have to be considered.
  • System responsiveness relates to the question: "How long do users have to wait at the computer?"
    When attempting to improve the system's responsiveness, developers and UI designers strive to reduce the users' waiting times in spite of the fact that some system processes – for example, the ones that the users just had started – have not finished yet. That sounds like a paradox and you can imagine that some creativity is needed to come up with good solutions here. The question above sounds as if we were in a purely technical domain, but this is not the case, as waiting times have an impact on users. Therefore, this aspect requires close cooperation between technology and UI design, and thus figure 1 puts it in both fields.
  • Perceived performance relates to the question: "How do users perceive the system's and their performance?"
    It indicates that there is often a difference between objective performance and the subjective impression that it makes on the users. It is not included in figure 1.

Overview of system performance, system responsiveness, and human performance and the related questions

Figure 1: Overview of system performance, system responsiveness, and human performance and the related questions

 

Time Ranges

Extended Table

This is a more extended version of the time range table presented in the main article (from Human Performance at the Computer – Part 2: Making Applications More Responsive):

Time Range Human Aspect User Interface:
Acceptable Response Times
User:
Response/Feedback Does Not Appear Timely
Comments on Untimely Response
0.1 sec
(0.05-0.2)
Perception Acknowledge user input
(direct manipulation: key press, mouse click, open/close menu, highlighting, ...)
Perception of smooth animations and cause-and-effect relationship breaks down Must not happen!
1.0 sec
(0.2-2.0)
Dialog,
Operation
Present result of simple tasks
(navigation, open new window), finish unrequested actions (auto-save)
Engaged user-system dialog breaks down Should not happen; provide feedback, allow user to abort the process
3 sec
(2.0-5.0)
Cognition,
Attention, Motivation
Present result of common tasks (simple search/calculation) User has time to think: the system is perceived as slow, the user's focus starts to wander, and the user may turn to other tasks
10 sec
(5.0-15)
Present result of complex tasks (complex search/calculation) User loses focus on task and may turn to other tasks
>15 sec Present result of very complex tasks (extensive search/calculation) User gets annoyed; detrimental to productivity and motivation

Table 1: Human time ranges

*) Because these times are only rough guides, most authors simply list the powers of 10, such as 0.1, 1, and 10 seconds; we have extended the numbers into consecutive ranges but please do not take the transition points too literally. The limit of 2 seconds for the dialog level may already be too high.
**) We took the terms "simple," "common," and "complex" tasks directly from the literature. In our opinion, they are only of limited use because they do not clearly describe the task types at the respective levels.

Graphic

The following graphic offers a graphical overview of human time ranges and the corresponding tasks and user reactions:

Human Time Ranges

Figure 1: Graphical description of human time ranges (click image for larger version)

 

References

  1. Card, S. K., Robertson, G. G., and Mackinlay, J. D. (1991). The information visualizer: An information workspace. Proceedings of ACM CHI'91 Conf., 181-188.
  2. Alan Cooper, Robert M. Reimann & Dave Cronin (2007). About Face 3.0: The Essentials of Design. John Wiley & Sons (Chapter: Optimizing for Responsiveness, Accommodating Latency; p.220-221).
  3. Jeff Johnson (2007). GUI Bloopers 2.0: Common User Interface Design Don'ts and Do's. Morgan Kaufmann Publishers (Chapter 1: First Principles; Basic Principle 8: Design for Responsiveness; Chapter 7: Responsiveness Bloopers).
  4. A. Newell (1994). Unified Theories of Cognition. Harvard University Press.
  5. Ben Shneiderman & Cathérine Plaisant (2004). Designing the User Interface (4th Edition). Pearson Addison-Wesley (Chapter 11: Quality of Service, p. 453ff).
  6. Jakob Nielsen (1993). Usability Engineering. San Diego, CA: Academic Press. (Chapter 5: Usability Heuristics).
  7. Robertson, G., Card, S., Mackinlay, J. (1989). The Cognitive Co-Processor Architecture for Interactive User Interfaces. Proceedings of the ACM Conference on User Interface Software and Technology (UIST’89), November 1989, ACM Press, p. 10-18.
  8. Robertson, G., Card, S., Mackinlay, J.(1993). Information Visualization Using 3D Interactive Animation.Communications of the ACM, 36(4), 56-71.
  9. Waloszek, G., Kreichgauer, U. (2009). User-Centered Evaluation of the Responsiveness of Applications. In: T. Gross et al. (Eds.), INTERACT 2009, Part I, LNCS 5726, pp. 239–242.

 

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