Ada berbagai macam definisi usability. Masing-masing peneliti memiliki argumen dalam menentukan kriteria apa saja yang termasuk dalam usability. Berbagai pandangan tersebut menimbulkan perdebatan, namun belum diketahui secara pasti manakah definisi terbaik untuk usability. Bagi beberapa peneliti, usability yang baik, adalah yang dilaporkan pada developer dan stake holder, sehingga dapat dilakukan perbaikan desain perangkat lunak.
Berikut ini beberapa definisi usability
| Sharp, et.al (2002) | Usability memastikan bahwa produk mudah dipelajari, efektif digunakan, dan menyenangkan dari perspektif pengguna |
| Dix, et.al (2004) | Usability merupakan tujuan akhir dari desain interaktif sistem. |
| Keberhasilan sebuah produk, mencakup tiga kata “guna”, yaitu “berguna”, “dapat digunakan” dan “digunakan” | |
| berguna : memenuhi apa yang dibutuhkan penggunanya, misalkan menjalankan musik, memasak makan malam, melakukan format dokumen | |
| dapat digunakan : pengguna dapat menggunakannya dengan mudah dan alami, misalkan tanpa kesalahan berbahaya | |
| digunakan : membuat orang ingin menggunakannya, menarik, menyenangkan | |
| ISO 25010 (2011) | sejauh mana produk atau sistem dapat digunakan oleh pengguna tertentu untuk mencapai tujuan tertentu dengan efektivitas, efisiensi dan kepuasan dalam konteks tertentu digunakan. |
| usability dapat diukur sebagai karakteristik kualitas produk, maupun diukur secara langsung yang merupakan bagian dari kualitas penggunaan | |
| Nielsen (1993) | Kegunaan adalah atribut kualitas yang menilai betapa mudahnya antarmuka yang digunakan. Kata “kegunaan” juga mengacu pada metode untuk meningkatkan kemudahan penggunaan selama proses desain. |
Perbedaan karakteristik dan terminologi dalam usability saya petakan ke dalam tabel berikut ini
| No | Karakteristik | Sinonim | Definisi | Sumber |
| 1 | Learnability | Easy to learn | Learnability refers to how easy a system is to learn to use. It is well known that people don’t like spending a long time learning how to use a system. | Sharp, et.al (2002) |
| Learnability is the ease with which new users can begin effective interaction and achieve maximal performance. | Dix, et.al (2004) | |||
| Degree to which a product or system can be used by specified users to achieve specified goals of learning to use the product or system with effectiveness, efficiency, freedom from risk and satisfaction in a specified context of use | ISO 25010 (2011) | |||
| How easy is it for users to accomplish basic tasks the first time they encounter the design? | Nielsen (2012) | |||
| To what degree can the transformation language and tool be learned in a reasonable timescale and with reasonable effort? | Kolahdouz et.al (2014) | |||
| Does the BPL-Framework enable users to learn its application? | Terenciani, et.al (2015) | |||
| 2 | Effectiveness | Effective to use | Effectiveness is a very general goal and refers to how good a system is at doing what it is supposed to do. | Sharp, et.al (2002) |
| Accuracy and completeness with which users achieve specified goals | ISO 25010 (2011) | |||
| 3 | Efficiency | Efficient to use | Efficiency refers to the way a system supports users in carrying out their tasks. | Sharp, et.al (2002) |
| Resources expended in relation to the accuracy and completeness with which users achieve goals | ISO 25010 (2011) | |||
| Once users have learned the design, how quickly can they perform tasks? | Nielsen (2012) | |||
| 4 | Memorability | Easy to remember how to use | Memorability refers to how easy a system is to remember how to use, once learned. | Sharp, et.al (2002) |
| When users return to the design after a period of not using it, how easily can they reestablish proficiency? | Nielsen (2012) | |||
| 5 | User error protection | Safe to use (safety) | Degree to which a system protects users against making errors | ISO 25010 (2011) |
| Safety involves protecting the user from dangerous conditions and undesirable situations | Sharp, et.al (2002) | |||
| 6 | Errors | How many errors do users make, how severe are these errors, and how easily can they recover from the errors? | Nielsen (2012) | |
| 7 | Satisfaction | Degree to which user needs are satisfied when a product or system is used in a specified context of use | ISO 25010 (2011) | |
| 8 | User interface aesthetics | Satisfaction | How pleasant is it to use the design? | Nielsen (2012) |
| Degree to which a user interface enables pleasing and satisfying interaction for the user | ISO 25010 (2011) | |||
| 9 | Have good utility (utility) | Utility refers to the extent to which the system provides the right kind of functionality so that users can do what they need or want to do. | Sharp, et.al (2002) | |
| 10 | Flexibility | Flexibility is the multiplicity of ways in which the user and system exchange information | Dix, et.al (2004) | |
| 11 | Accessibility | Technical Accessibility | Degree to which a product or system can be used by people with the widest range of characteristics and capabilities to achieve a specified goal in a specified context of use | ISO 25010 (2011) |
| Contains all the attributes that allow physically impaired users to play the video game | Fernandez, et.al (2012) | |||
| 12 | Robustness | Robustness is the level of support provided to the user in determining successful achievement and assessment of goals | Dix, et.al (2004) | |
| 13 | Appropriateness recognizability | Degree to which users can recognize whether a product or system is appropriate for their needs | ISO 25010 (2011) | |
| 14 | Operability | Ease of operation | Degree to which a product or system has attributes that make it easy to operate and control | ISO 25010 (2011) |
| Ease of use | The capability of an approach feature to enable the user to operate and control it. | Dominguez, et.al (2012) | ||
| contains all the attributes of the video game that facilitate players’ control and operation, both inside and outside gameplay | Fernandez, et.al (2012) | |||
| Ease of use | Does the BPL-Framework make it easy for users to operate and control it? | Terenciani, et.al (2015) | ||
| Ease of Interaction | Elements related to the adequacy and quality of text contents, icons, and controls | Torrente, et.al (2013) | ||
| 15 | Understandability | Comprehensibility | The capability of being understood and the extent to which an approach feature is clear, without ambiguity, and easily comprehensible | Dominguez, et.al (2012) |
| Simplicity | How easy is it to comprehend a transformation specification? | Kolahdouz et.al (2014) | ||
| The degree to which an approach feature has a straightforward design easily understood. | Dominguez, et.al (2012) | |||
| 16 | Attractiveness | The extent to which an approach feature is sufficiently attractive for users. | Dominguez, et.al (2012) | |
| Contains the attributes that make a video game more appealing to the players | Fernandez, et.al (2012) | |||
| How acceptable is the language and tool for the user? | Kolahdouz et.al (2014) | |||
| Is the BPL-Framework attractive to the user? | Terenciani, et.al (2015) | |||
| 17 | Interpretability | The extent to which an approach feature is organized into suitable units of information for the user’s skill | Dominguez, et.al (2012) | |
| 18 | Helpfulness | Help | Contains the attributes of the video game that provide help when the players need it | Fernandez, et.al (2012) |
| Elements related to the help provided to the user while browsing | Torrente, et.al (2013) |
Beberapa artikel membahas penyesuaian jenis dan jumlah karakteristik dari standar yang telah ditetapkan ISO 25010. Dominguez, et.al menambahkan karakteristik simplicity, interpretability, understandability dan attractiveness Kolahdouz, et.al menambahkan understandability dan attractiveness . Fernandez, et.al menambahkan karakteristik ease of use, helpfulness, technical accessibility, dan attractiveness dalam evaluasi usability video game. Terenciani, et.al menyebut attractiveness, ease of use dan learnability merupakan karakteristik dari operability, sedangkan dalam ISO 25010, operability merupakan karakteristik tersendiri dalam usability.
Understandability, simplicity, comprehen sibility merujuk pada kemampuan untuk dipahami, fitur pendekatan yang jelas, tanpa ambiguitas [8][9]. Understandability merupakan karakteristik yang muncul pada ISO 9126-1, dan pada ISO 25010 memiliki nama baru yang lebih akurat, yaitu appropriateness recognisability.
Appropriateness recognizability merupakan tingkat pengenalan pengguna terhadap sistem yang sesuai dengan kebutuhan pengguna.
Karakteristik attractiveness sebenarnya merupakan terminologi pada ISO 9126-1, dan sudah tidak digunakan lagi pada ISO 25010, istilah tersebut berganti dengan user interface aesthetics. Namun, beberapa peneliti masih menggunakan istilah tersebut dalam pengukuran usability. Hal ini menandakan bahwa attractiveness masih relevan digunakan pada pengukuran perangkat lunak tertentu, seperti video game, pengolah kata, and website. Ketersediaan bantuan kepada pengguna diwakili oleh karakteristik helpfulness, atau help.
Kesimpulan :
- Pada beberapa kasus terdapat penyesuaian jenis dan jumlah karakteristik dari standar yang telah ditetapkan ISO 25010.
- Dari keseluruhan karakteristik ISO 25010, learnability merupakan karakteristik paling dominan dalam pengukuran usability perangkat lunak.
- Hasil dari analisis tersebut, kemudian dibentuk usulan taksonomi usability berdasarkan performa pengguna (learnability, satisfaction, effectiveness, errors) dan performa sistem (user error protection, user interface aesthetics, accessibility, efficiency, operability, helpfulness).
- Taksonomi tersebut membentuk hirarki model, dimana setiap karakteristik memiliki sub karakteristik di bawahnya. Usulan taksonomi usability dijadikan acuan untuk evaluasi usability perangkat lunak.
Dipublikasikan dalam seminar nasional inovasi teknologi, UN PGRI Kediri, 2017