Prioritizing Web Usability Nielsen and Loranger Chapter 4: Prioritizing Your Usability Problems Paul Ammann SWE 432 Design and Implementation of Software for the Web

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

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

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

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?

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

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

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