Human-Computer InteractionOverview

● Benefits of more usable Websites● History of HCI● Goals of HCI● User-Centered Methodology

Have you ever:

● been unable to find something in a website that you know is there?

● recevied a useless or misleading error message?● wondered why a website needs to know your e-

mail address?● left a site for fear information you provided might

be misused?

It should not be that way

● Websites can be designed to be:– Pleasant & convenient for users.– where users can acomplish their goals.

● The Key is to think about users– Learn about them– Observe them– Interview them

Benefits of usable Websites

● Gaining a competitive edge● Reducing development/maintenance costs● Improving user productivity● Lowering support costs

Gaining a competitive edge

● Number of hits to a site vs conversion rate– Number of hits only counts visitos not sales– Conversion rate is the percentage of visitors who take

an action you want them to take– Higher conversion rates leads to lower sales cost– Most significant factor in higher conversion rate is the

ease of use– Average conversion rates were 3.2% in 2003

Reducing development/maintenance costs

Learn about users first to avoid:● Implementing features that users do not want.● Features that are annoying or inefficient.● Making changes late in the development cycle

(high cost).● Lower life-cycle maintenance cost.

● Most maintenance costs come from unmet or unforeseen user needs

Improving User Productivity

● e-commerce: users find what they want—and succeed in buying it

● company intranet: employees become more efficient

Lowering support costs

● Calls to costumer support are very expensive● Average service call is $12 to $250● Wall-Mart shut down shopping site for three weeks (1999)

● Customer confusion affecting support systems● A Website that reduces support calls can result in

tremendous savings

What is HCI?

“Human Computer Interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of the major phenomena surrounding them.”

● Special Interest Group on Human-Computer Interaction (SIGCHI) of the Association for Computing Machinery (ACM)

Interactive Computing Systems

Examples:● A PC used for Web browsing: e-commerce,

database● Embedded devices: automobiles, planes● Handheld devices: cells phones, GPS, Palm pilots,

etc.● Software for multi-user collaboration

Computing Cost Shift

40 year ago:cost of one computer = salary of 200 programmers

today:

salary of one programmer = cost of 200 computers

Now:

goal is to make computers easy to use, to save user time

How to make computers easy to use?

● Applying principles of Human-Computer Interaction– Consider physical limitations– Consider the environment where it is located

● By being and advocate of the user – an HCI practitioner listens to the users and

communicates with the development team

Goals of HCI

Develop or improve:

– Safety– Utility– Effectiveness– Efficiency– Usability– Appeal

. . . of interactive systems that involve computers

Safety

● Safety of Users– Air traffic control– Hospital intensive care– Hospital radiation unit

● Safety of Data– Protection of files from tampering– Privacy and security

Utility

● what services a system provides:– Information– Instruction– Purchases– Banking transactions– Investing– Etc.

Effectiveness

● User’s ability to achieve goals:– Find desired information – Enter credit card data– Arange a payment– Able to upload a class assignment

● A web site might provide all necessary services, but if users can’t find the items they want to buy, the site lacks effectiveness

Efficiency

● Measures how quickly users can accomplish their goals using the system

Usability

● Ease of learning● Ease of use

Appeal

● How well users like the system– First impressions – Long-term satisfaction