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ISO-9241 standard defines Satisfaction with the product as �comfort and relevance of application�.
In contrast to Efficacy and Productivity, where we observe and evaluate the user�s actions, Satisfaction aims at subjective thoughts of the user.
There are two widespread methods of Satisfaction measurement.
Method 1: Satisfaction is measured through a formalized questionnaires featuring satisfaction scales.
Each questionnaire contains a number of statements reflecting subjective user�s opinion on interaction with the product. For example, �I like the way interface looks� or �I believe the product to be too complicated�.
Each scale features between 3 and 11 answers. Here is the example of a 5-point scale:
Weight � numeric value of the satisfaction coefficient, which depends on the answer.
Weight for a 5-point scale can be estimated differently, e.g. from -2 to +2, from 1 to 5 or from 0 to 4.
The questions and statements concerning the product might sound both positive and negative.
A positive question with weight driven by answers:
| No |
Rather not |
Neutral |
Rather yes |
Yes |
| 0 |
1 |
2 |
3 |
4 |
Example: �I am satisfied with the speed of this product�
A negative question with weight driven by answers:
| No |
Rather not |
Neutral |
Rather yes |
Yes |
| 4 |
3 |
2 |
1 |
0 |
Example: �I often made mistake while doing tasks�
����:
R � the number of respondents
Q+ � the number of positive questions featuring in the questionnaire
Q- � the number of negative questions
pij+ � weight for the answer to a positive question (0-4) for i-scenario and j-respondent
pij- � weight for the answer to a negative question (4-0) for i-scenario and j-respondent
the average satisfaction (S) is estimated through the following formula:
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(10) |
Statistical error of Satisfaction:
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(11) |
Total satisfaction with the product:
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(12) |
Satisfaction questionnaires applied for our tests:
- SUS (System Usability Scale) suggested by the Digital Equipment Corporation � 1986
(10 questions, a 5-point scale)
- QUIS (Questionnaire for User Interaction Satisfaction) suggested by the Human-Computer Interaction Lab (HCIL) at University of Maryland at College Park � 1990
(24 questions, a 10+1 point scale)
- SUMI (Software Usability Measurement Inventory) suggested by the Human Factors Research Group � 1993
(50 questions, a 3-point scale)
- CSUQ (Computer System Usability Questionnaire) suggested by IBM � 1995
(19 questions, a 7+1 point scale)
Besides, we apply ISO-20282 standard ("Easy of operation of everyday products: Test method for walk-up-and-use products"), which expands ISO-9241 standard � applicable for products aimed at day-to-day use. This standard presupposes application of extra Smiley Scale � Kunin, 1955.
The Smiley Scale method. The respondent is to choose one smiley in five to reflect his/her satisfaction with a certain action:
Weight coefficients range from -2 to +2.
Method 2. The Word Method enables to uncover subjective associations generated by the product.
One of the Word lists versions comprises 118 adjectives with positive and negative connotation. � 2002 Microsoft Corporation. All rights reserved.
Each user is to highlight words reflecting his/her interaction with the product. The words feature in alphabetical order and negative ones are mixed with the positive.
The aggregated results enable to draw a diagram reflecting the general impression of users confronted with the product. Fr convenience purposes positive associations are highlighted in green and negative � in red. The Associations diagram is aligned in accordance with the number of respondents.
Associations diagram for 11 respondents:
If:
R � number of respondents
A+j � number of positive words-associations provided by j-respondent
A-j � number of negative words-associations provided by j-respondent
The total Associate Satisfaction is estimated through the following formula:
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(13) |
Further: Methods
Users and Goals | Effectiveness | Efficiency | Satisfaction | Methods
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