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Usability 101. Dr. Lam TECM 3200. What is usability?. Definition differs depending on who you ask “Usability means making products and systems easier to use, and matching them more closely to user needs and requirements.”. Why is usability important?.

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Usability 101

Usability 101

Dr. Lam

TECM 3200

What is usability
What is usability?

  • Definition differs depending on who you ask

    “Usability means making products and systems easier to use, and matching them more closely to user needs and requirements.”

How long do people stay on websites
How long do people stay on websites?

Roughly speaking, there are two cases:

  • bad pageswill last a few seconds; and

  • good pages may be allocated a few minutes.

Experiment 1
Experiment #1

Answer the following questions in 10 seconds:

  • What does the company do?

  • How is this company’s website relevant to me?

  • What is the purpose of the site?

    See each website link on the next slide.

Experiment 11
Experiment #1




So how do users distinguish good from bad
So how do users distinguish good from bad?

  • Remember, they take about 10 seconds to make an evaluation:

    • Initial interface evaluation

    • Ascetics

    • Clear call to action

    • What else?

Experiment 2
Experiment #2

  • Let’s try it again:

    • What does the company do?

    • How is this company’s website relevant to me?

    • What is the purpose of the site?




What makes a website usable
What makes a website usable?

  • Intuitive design: a nearly effortless understanding of the architecture and navigation of the site

  • Ease of learning: how fast a user who has never seen the user interface before can accomplish basic tasks

  • Efficiency of use: How fast an experienced user can accomplish tasks

  • Memorability: after visiting the site, if a user can remember enough to use it effectively in future visits

  • Error frequency and severity: how often users make errors while using the system, how serious the errors are, and how users recover from the errors

  • Subjective satisfaction: If the user likes using the system

Usability methods
Usability Methods

  • Heuristic Evaluations

  • User-Centered Research (usability study)

  • Using big data (metrics)

Heuristic evaluations
Heuristic Evaluations

Usability experts review your site’s interface and compare it against accepted heuristics (usability principles). The analysis results in a list of potential usability issues.


  • It can provide some quick and relatively inexpensive feedback to designers.

  • You can obtain feedback early in the design process.

  • Assigning the correct heuristic can help suggest the best corrective measures to designers.

  • You can use it together with other usability testing methodologies.

  • You can conduct usability testing to further examine potential issues.


  • It requires knowledge and experience to apply the heuristics effectively.

  • Trained usability experts are sometimes hard to find and can be expensive.

  • You need multiple experts and aggregate their results.

  • The evaluation may identify more minor issues and fewer major issues.

Nielsen s heuristics
Nielsen’s Heuristics

  • Visibility of system statusThe system should always keep users informed about what is going on, through appropriate feedback within reasonable time.

  • Match between system and the real worldThe 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.

  • User control and freedomUsers 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 standardsUsers should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.

  • Error preventionEven 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.

Nielsen s heuristics cont
Nielsen’s Heuristics Cont.

  • Recognition rather than recallMinimize 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 useAccelerators—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 designDialogues 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 errorsError messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.

  • Help and documentationEven 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.

Usability study
Usability Study

  • Usability testing is a technique used to evaluate a product by testing it with representative users. In the test, these users will try to complete typical tasks while observers watch, listen and takes notes.

  • Your goal is to identify any usability problems, collect quantitative data  on participants' performance (e.g., time on task, error rates), and determine participant's satisfaction with the product.

Usability study1
Usability Study


  • Time

  • Cost


  • Feedback from representative users (removes potential expert bias)

  • Reveals problems in a task-based manner (not based on website components)

  • Think aloud protocol

Usability testing process
Usability Testing Process

  • Develop the test plan

    • Scope

    • Purpose

    • Schedule & Location

    • Sessions

    • Equipment

    • Participant

    • Scenarios

    • Metrics

    • Roles

Usability testing process cont
Usability Testing Process Cont.

2. Create test scenarios

  • Brief- In which government building can you find Bertrand Adams' 1937 painting Early Settlers of Dubuque?

  • Elaborated - Your grandfather told you that he posed for Bertrand Adams when he was painting his large 1937 masterpiece, Early Settlers of Dubuque. You heard that the painting is displayed in a Federal building. In which building can this artwork be found?

    3. Select testing metrics

  • Critical and non-critical errors

  • Task completion

  • Error rate

  • Time on task

  • Subjective measures

  • Likes, dislikes, recommnedations

Usability process cont
Usability Process Cont.

4. Select Participant Pool

  • Number, recruitment, cost

    5. Develop testing materials

  • Data collection sheets

  • Pre-test questionnaire

  • Post- test questionnaire

  • Facilitator’s script

  • Consent forms

    6. Conduct usability test

Big data
Big Data

  • 90% of the data in the world was created in the last 2 years alone

  • Generated from a multitude of sources including social media, digital pictures and video, online purchase records, cell phone gps data, and website metrics

Big data1
Big Data


  • Difficult to interpret

  • Requires site visitors

  • Is NOT the answer to all web problems


  • Free!

  • It’s big

  • Unbiased

Common web metrics
Common Web Metrics

  • Unique visitors: The total number of individual visitors to your site during a specific period of time, not counting repeat visits by the same individual

  • New vs. Repeat Visitors: A comparison of your unique visitors vs. the number of visitors who came back more than once

  • Traffic sources: A comparison of your unique visitors vs. the number of visitors who came back more than once

  • Most/Least popular pages

  • Indexed pages

  • Landing page conversion rate

  • Bounce rate

Information overload
Information Overload?

  • No method is perfect- It’s best to use a combination of methods

  • Most importantly, how you interpret the data is of utmost importance

  • Misinterpretation can be more costly than no usability testing at all

Interpreting data
Interpreting data

  • Look for trends (i.e. – not merely one interesting anomaly)

  • Look for consensus among users (in a user test) or among experts (in a heuristic)

  • Consider sample size and hedge accordingly

  • Be overly cautious

Experiment 3
Experiment #3

Opinions vs. Heuristic Evaluation

  • Opinion group

    • In pairs, rank the homepage for the following the websites from best to worst

    • Write down some reasons for your ranking

  • Heuristic group

    • In pairs, complete the home page heuristic evaluation for each site.

    • Rank the three sites based on the quantitative score

Experiment 31
Experiment #3




Resources and references
Resources and References