Related characteristics
understandability
learnability
operability
explicitness
customisability
attractivity
clarity
helpfulness
user-friendliness
Understandability
Description
Attributes of software that bear on the users' effort for recognising the logical concept and its applicability.
Indicators
1. rated understandability
The understandability of the instructions, menus, commands, pictograms, icons, help information, instructions, manuals, etc., of the software product as rated by the user.
Source: QUINT
Scale: ordinal
Validity: **
Protocol:
1. Show the used text, menus, icons, etc., to a representative group of users;
2. Let the users decide on understandability (just yes or no);
3. Appreciate understandability as:
high: 80% or more of the selected group found the material understandable;
average: 60% to 80% found the material understandable;
low: less than 60% found the material understandable.
2. readability score
Rating of the readability of the software product (on-screen messages, documents, pictograms, etc.).
Source: QUINT
Scale: interval
Validity: **
Protocol:
1. Determine the average number of words per sentence;
2. Determine the percentage of unfamiliar words according to the standard dictionary;
3. Calculate the readability score according to the Dale-Chall Readability formula [Höc84]:
readability score = 0.1579 nfw + 0.0496 sl + 3.6305
with nfw = percentage unfamiliar words and sl = average sentence length.
Note: Readability score determines the difficulty of a text with regard to reading levels in the American school and college system. A higher score denotes a text which is less easy to read. The reading levels are as follows:
1 - 8: grade school;
9 - 12: high school;
13 - 16: college.
This measurement protocol is intended for English/American documents. Adapting this protocol to a different language requires research.
This indicator has nothing to do with meaningfulness of a text, but merely indicates word usage and sentence length.
3. concept clearness
The proportion of functions that can be explained by using clear, familiar models to illustrate concepts. This represents the degree to which the functions and conventions of a software product are explained through models using familiar concepts from the everyday world.
Source: ISO
4. availability of demonstration software
The proportion of functions presented to the users through demonstration software.
Source: ISO
5. usage clearness
The ratio of functions explained or by using clear models or presented to the user through demonstration software or anyway described.
Source: ISO
6. availability of input/output data items list
For functions with input or output operations, the number of input/output items that are listed.
Source: ISO
7. recognisability of modifiable parameters
The proportion of parameters that are identified as being either modified or fixed.
Source: ISO