INFO3315 Week 4

Personas, TasksGuidelines, Heuristic Evaluation

Guidelines

For design and heuristics evaluation

Fine-grained guidelines

Easier for less experienced evaluators

Text guidelines

• Avoid negatives (sic)• Short simple sentences.• Active voice (not passive).• AVOID UPPER CASE

http://guidelines.usability.gov/

• Section 1, Make Action Sequences Clear• Section 2, Avoid Jargon• Section 3, Use Familiar Words• Section 4, Define Acronyms and Abbreviations• Section 5, Use Abbreviations Sparingly• Section 6, Use Mixed Case with Prose• Section 7, Limit the Number of Words and Sentences• Section 8, Limit Prose Text on Navigation Pages• Section 9, Use Active Voice• Section 10, Write Instructions in the Affirmative• Section 11, Make First Sentences Descriptive

Coarse-grained guidelines

Challenging for less experienced evaluators

Heuristic evaluation aka Usability Inspection

and guidelines

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Nielsen’s original heuristics

• Visibility of system status.• Match between system and real world.• User control and freedom.• Consistency and standards.• Error prevention. • Recognition rather than recall.• Flexibility and efficiency of use.• Aesthetic and minimalist design.• Help users recognize, diagnose, recover from errors.• Help and documentation.http://www.nngroup.com/articles/ten-usability-heuristics/

• Visibility of system status The system should always keep users informed about what is going on, through appropriate feedback within reasonable time. – eg make visible the delay as a file is being loaded– < .1 second instantaneous, < 1 second perceptible, > 1 second let user know

they need to wait• Match between system and the real world The system should speak

the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.– eg use terms the user will understand

• User control and freedom Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.

• Consistency and standards Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions. – Challenges of standards

• Error prevention Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.

• Recognition rather than recall Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.

• Flexibility and efficiency of use Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.

• Aesthetic and minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.

• Help users recognize, diagnose, and recover from errors Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.

• Help and documentation Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

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Activity: Identify potential trade-offs

• Visibility of system status.• Match between system and real world.• User control and freedom.• Consistency and standards.• Error prevention. • Recognition rather than recall.• Flexibility and efficiency of use.• Aesthetic and minimalist design.• Help users recognize, diagnose, recover from errors.• Help and documentation.

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Main stages of heuristic evaluation

• Preliminaries– Agreed set of heuristics to use;– Programming team member overviews system;– And team member is available throughout;– Set of tasks;

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Main stages of heuristic evaluation

• Evaluation:– Each expert works independently through the UI;– Team member records problems, so expert can simply

state them (single person works well, so they bring all details together);

– Also answers any questions (eg expert gets stuck, cannot find how to do a task, may need help with domain expertise aspects)

– Multiple passes (overview, then detailed)– Results in a set of identified failures to match the

heuristics (part of interface, violated heuristic)

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Main stages of heuristic evaluation

• Concluding summary– Summarise all the flaws– Rate these in terms of severity

Severity ratingshttp://www.nngroup.com/articles/how-to-rate-the-severity-of-usability-problems/

• “The severity of a usability problem is a combination of three factors:

• The frequency with which the problem occurs: Is it common or rare?

• The impact of the problem if it occurs: Will it be easy or difficult for the users to overcome?

• The persistence of the problem: Is it a one-time problem that users can overcome once they know about it or will users repeatedly be bothered by the problem?”

• 0 = I don't agree that this is a usability problem at all 1 = Cosmetic problem only: need not be fixed unless extra time is available on project 2 = Minor usability problem: fixing this should be given low priority 3 = Major usability problem: important to fix, so should be given high priority 4 = Usability catastrophe: imperative to fix this before product can be released

Severity ratingshttp://www.nngroup.com/articles/how-to-rate-the-severity-of-usability-problems/

Summarising the resultsDescription of problem Heuristics violated S1 S2 S3

Hard to find the Archive button Consistency … 0 1 2

Scroll bar not visible Visibility…, Match system and real world

3 2 4

User has to remember ID from last screen

Recognition rather than recall 4 4 4

Interface uses language that is not meaningful to user – select bundle for student data

Match system and real world 2 2 3

Instructions say “Circle all selections” but there are check boxes

Match system and real world

Shows which evaluators found which usability problems in HE of a banking system. Each row is an evaluator (n=19) and each column is a flaw (n=16)Black squares show where evaluator found the problem.The rows are sorted with most successful evaluators at the bottom.The columns are sorted with easiest to find problems at right.

http://www.nngroup.com/articles/how-to-conduct-a-heuristic-evaluation/

What does this graph tell you?

19www.id-book.com

No. of evaluators & problems

20www.id-book.com

Discount evaluation

• Heuristic evaluation is referred to as discount evaluation when 5 evaluators are used.

• Empirical evidence suggests that on average 5 evaluators identify 75-80% of usability problems.

Critical to success

• Set of heuristics• Set of tasks• Prototype interface (can be story boards, so

long as they have enough of the key details)• Experts!!!

Advantages

• No users– No need to recruit users– No ethical issues

• Low cost – “discount” with just 5 expert evaluators

• Very useful for software developers

Disadvantages

• Relies on experts ….– Callibre– Biases– Domain expertise– Can be expensive

• Can find trivial problems that may not really matter to actual users