Related characteristics
understandability
learnability
operability
explicitness
customisability
attractivity
clarity
helpfulness
user-friendliness
Operability
Description
Attributes of software that bear on the users' effort for operation and operation control.
Indicators
1. expert judgement on operability
The extent to which the software product presents functionality to the user without hindrance, as judged by a team of experts in this field.
Source: QUINT
Scale: ordinal
Validity: **
Protocol:
1. Select one or more experts to judge operability;
2. Let the experts determine which technical actions appear in the user interface;
3. Let the experts express operability as: high: there is little or no appeal to users' technical knowledge; average: users have to perform non-functional (i.e. technical) actions; low: a high appeal is made to users' technical knowledge.
2. operability compared with sample
The operability of the software product is compared to the operability of a predetermined sample product.
Source: QUINT
Scale: ordinal
Validity: **
Protocol:
1. Select one or more experts to judge operability;
2. Let the experts determine to which extent operability of the software product matched operability of the sample product;
3. Let the experts express operability as one of the following:
a. operability of the software product matches the sample product;
b. operability of the software product to a large extent matches the sample product;
c. operability of the software product only partially matches the sample product;
d. operability of the software product does not match the sample product.
3. operability in practice
The extent to which the software product presents functionality to the user without hindrance, as judged by users after a period of use.
Source: QUINT
Scale: ordinal
Validity: *
Protocol:
1. Select a representative group of users;
2. Let the users express their judgement in one of the following options: high: little or no appeal is made to users' technical knowledge; average: users have to perform non-functional (i.e. technical) actions; low: a high appeal is done to users' technical knowledge.
4. set-up installation time
The sum of time required for the installation process, including preparations, execution of environment set-up and verification.
Source: ISO
5. set-up installation procedures with human interaction
The number of steps for set-up installation operation which require human interaction (for everyday use).
Source: ISO
6. availability of set-up performance
The ratio of number of set-up performances available and the total number of performances: availability of set-up installation restart, availability of set-up installation confirmation functions.
Source: ISO
7. ease of set-up
The average time required to set up the software or system.
Source: ISO
8. availability of set-up installation restart
The number of points at which users can make a pause and from which the installation operation can be restarted.
Source: ISO
9. availability of set-up installation preparation
The number of types and amount of computer resources including system, hardware, software and personnel to be employed for installation.
Source: ISO
10. availability of set-up installation confirmation
The number of steps for installation confirmation operation which are necessary to validate that the software or system has been successfully installed and is ready to be used adequately.
Source: ISO
11. default value availability ratio
The ratio of operating commands having default values to the total number of operating commands.
Source: ISO
12. command uniformity
The proportion of operating commands having uniform formats, which are based on common-sense and comprehensible rules.
Source: ISO
13. consistency of terms in message
The proportion of system message terms that are standardised.
Source: ISO
14. message clearness
The proportion of system messages from software or system in which causes and corresponding action are clearly identified by the user who received those messages.
Source: ISO
15. skill level adaptability
The proportion of functions for which operating methods can be selected to correspond to the user's level of skill.
Source: ISO
16. uniformity of screen manipulating operations
The proportion of types of screen-manipulating operations using common basic conventions or patterns.
Source: ISO
17. stability of input/output areas on display
The proportion of input/output screen formats designed with standardised formats in which the position and form of input/output fields are commonly laid out.
Source: ISO
18. number of keystrokes
The number of keystrokes of operation required by the user to carry out the work. Those keystrokes include strokes of key click, button click, screen touch, pen move, mouse move, etc.
Source: ISO
19. availability of reduced effort for repeated operations
The ratio of strokes required to repeat operation to the strokes required for the first operation to perform a specific task.
Source: ISO
20. mean time between human error operations
Average time interval between one operation error (human error operation) and the next.
Source: ISO
21. ultimate operation time
The time required for the operation, that is ultimately reduced and cannot be reduced anymore by further improvements.
Source: ISO
22. time for shutdown operation
The average time between the input of the system shutdown command at the beginning of shutdown operation and the time when shutdown is completed.
Source: ISO
23. guide function availability ratio
The ratio of available guide functions to the required ones for a given set of functions.
Source: ISO
24. human error operation cancellability ratio
The ratio of command/data entries that can be cancelled to the total command/data entries.
Source: ISO
25. ability to emphasise expressions
The ratio of number of actually implemented means to required ones which are provided to emphasise expressions to the user for a given set of functions. It is considered that colour, sound, brightness, and animation are means to emphasise expressions.
Source: ISO
26. response time for user
The elapsed time from the user input request or command to the nearest response to that request by the software or system. The first response to the request may be a state or progress report expressing that software or system is processing the request. At least mean, minimum and maximum time should be measured.
Source: ISO
27. display time
The elapsed time from the current display on screen after request to change, to the next complete display on screen. At least mean, minimum and maximum time should be measured.
Source: ISO