1. Prioritizing Web Usability Nielsen and Loranger Chapter 4: Prioritizing Your Usability Problems Paul Ammann http://cs.gmu.edu/~pammann/ SWE 432 Design and Implementation of Software for the Web

2. 9/4/20152 Overview What Makes Problems Severe The Scale of Misery Why Users Fail Is it Enough to Focus on the Worst Problems? Fixing the Web, Starting With The Worst Problems

3. 9/4/20153 How Severe Is The Problem? High Severity Problems Impose an Unacceptable Cost and/or Loss of Business: –Prevents Use of Site –Actively Drives Users Away: Dime Savings Bank (See Investor Relations)Dime Savings Bank Medium Severity Problems Cause –Confusion, Frustration, Some Lost Business Low Severity Problems: California State ParksCalifornia State Parks –Cosmetic and Irritating –But Do Not Individually Hurt Business A Rough and Ready Triage Approach

4. 9/4/20154 Example: Usability For Hospital Order- Entry System Dosage Listed in “Units of Medication”, i.e. Pills. –Subtle Message: One Pill = One Typical Dose –Solution: Interface Should List Typical Dosage Changes To Medication Dosage –If Old Order Not Cancelled, Patient Gets Sum of Medications –Similar to Double Debit In Online Bill Pay Moral: Always Check for Apparent Duplicate Requests Memory Overload: Each Patient Had Up To 20 Screens –Way Past the 7 +/- 2 Memory Limit –Staff Resorted to Paper Notes, With Data Entry At Shift End Moral: Sticky Notes Are a Bad Sign! Usability Matters

5. 9/4/20155 What Makes Problems Severe Frequency –How Many Users Will Encounter The Problem? Impact –How Much Trouble Does Problem Cause To Users Who Do Encounter It? Persistence –One-Off Problems That Users “Figure Out” Example: Login –Repeated Trouble Persistent Confusion Note: Persistently Abused Users Eventually Just Leave How Often? How Much? How Long?

6. 9/4/20156 The Scale of Misery Scale of Misery Usability Problems Are Weighted By Severity Score Note Huge Proportion Of Misery In Basic Functions: –Finding Information –Reading Information –Understanding Information Roughly 37% of Difficulties in Getting to Right Page Roughly 62% of Difficulties At Page Level –Bad Page or Page Progression Design Surprisingly, This is Still Legal

7. 9/4/20157 Why Users Fail Problems That Cause A User to Leave, Give Up, Or Mess Up Search and IA are Large Factors in Task Failure –You Can’t Succeed If You Can’t Find It Readability Less of A Factor –You Can Succeed, Even If You Are Annoyed Bottom Line: Search, Findability, Actual Info on Page

8. 9/4/20158 Is it Enough to Focus on the Worst Problems? Even Minor Problems Can Eventually Drive Users Away Next Chapters Focus On Key Areas: –Search –Navigation –Readability Understanding How To Help Users Succeed