ITIS 6010/8010 Usable Privacy & Security Dr. Heather Richter Lipford firstname.lastname@example.org Agenda Evaluation (from last time) Ethics & IRB Assignments update Chapter 2 & 3 discussion When to do evaluation? Summative – assess an existing system – judge if it meets some criteria Formative – assess a system being designed – gather input to inform design Which you do depends on maturity of prototypes and goals of evaluation Same techniques work for both Evaluation techniques Feedback from experts – Discount usability techniques: heuristic evaluation, cognitive walkthrough Observe users – Think-aloud & Cooperative evaluation Talk to users – Interviews & Focus groups Survey users – Questionnaires Test hypotheses – Experiments Typical User Study Bring participants into a controlled setting (lab) Introductions and consent Gather demographic data and give instructions Ask participant to do a set of tasks – Prototype can be simulated or partially functional Observe and record behavior Ask participant for feedback about interface Many variations Show or demonstrate mockup, storyboard, screenshots and gather feedback Observe or gather data about behavior in a natural setting Can be multiple sessions or just one Evaluation planning Decide on techniques, tasks, materials – What are usability criteria? – How much required authenticity? How many people, how long How to record data, how to analyze data Prepare materials – interfaces, storyboards, questionnaires, etc. Pilot the entire evaluation – Test all materials, tasks, questionnaires, etc. – Find and fix the problems with wording, assumptions – Get good feel for length of study General Recommendations Clearly identify evaluation goals Include both objective & subjective data – e.g. “completion time” and “preference” Use multiple measures, within a type – e.g. “reaction time” and “accuracy” Use quantitative measures where possible – e.g. preference score (on a scale of 1-7) Note: Only gather the data required; do so with minimum interruption, hassle, time, etc. Performing the Study Be well prepared so participant’s time is not wasted Describe the purpose of the evaluation – “I’m testing the product; I’m not testing you” Explain procedures without compromising results Session should not be too long , subject can quit anytime Never express displeasure or anger Data to be stored anonymously, securely, and/or destroyed Consent Why important? – People can be sensitive about this process and issues – Errors will likely be made, participant may feel inadequate – May be mentally or physically strenuous What are the potential risks (there are always risks)? “Vulnerable” populations need special care & consideration – Children; disabled; pregnant; students (why?) More later on IRB… Now what do you do? Start just looking at the data – Were there outliers, people who fell asleep, anyone who tried to mess up the study, etc.? Sort & prioritize the data Identify & summarize issues: – Overall, how did people do? – “5 W’s” (Where, what, why, when, and for whom were the problems?) Compile aggregate results and descriptive statistics Making Conclusions Where did you meet your criteria? Where didn’t you? What were the problems? How serious are these problems? What design changes should be made? – Update task analysis, scenarios, etc. Prioritize and plan changes to the design Modify prototypes and go again Experiments A controlled way to determine impact of design parameters on user experience Want results to eliminate possiblity of chance Hypothesis: What you predict will happen – More specifically, the way you predict the dependent variable (i.e., accuracy) will depend on the independent variable(s) Types of Variables Independent – What you’re studying, what you intentionally vary (e.g., interface feature, interaction device, selection technique) Dependent – Performance measures you record or examine (e.g., time, number of errors) Controlled – Factors you want to prevent from influencing results “Controlling” Variables Prevent a variable from affecting the results in any systematic way Methods of controlling for a variable: – Don’t allow it to vary e.g., all males – Allow it to vary randomly e.g., randomly assign participants to different groups – Counterbalance - systematically vary it e.g., equal number of males, females in each group The appropriate option depends on circumstances Example Do people complete operations faster with a black-and-white display or a color one? – Independent - display type (color or b/w) – Dependent - time to complete task (minutes) – Controlled variables - same number of males and females in each group – Hypothesis: Time to complete the task will be shorter for users with color display – Ho: Timecolor = Timeb/w Experimental Designs Within Subjects Design – Every participant provides a score for all levels or conditions Color B/W P1 12 secs. 17 secs. P2 19 secs. 15 secs. P3 13 secs. 21 secs. ... Experimental Designs Between Subjects – Each participant provides results for only one condition Color B/W P1 12 secs. P2 17 secs. P3 19 secs. P5 15 secs. P4 13 secs. P6 21 secs. ... Comparison Within subjects – More efficient: fewer trials and participants – But need to avoid “order effects” e.g. seeing color then b/w may be different from seeing b/w then color Between subjects – Simpler design & analysis because fewer order effects – Often shorter, so easier to recruit participant – More subjects for same statistical power Hypothesis Testing Tests to determine differences – t-test to compare two means – ANOVA (Analysis of Variance) to compare several means – Need to determine “statistical significance” “Significance level” (p): – The probability that your null hypothesis was wrong, simply by chance – p (“alpha” level) is often set at 0.05, or 5% of the time you’ll get the result you saw, just by chance Discount Evaluation Techniques Basis: – Observing users can be time-consuming and expensive – Try to predict usability rather than observing it directly – Conserve resources (quick & low cost) Expert reviewers used – HCI experts interact with system and try to find potential problems and give prescriptive feedback Example: Heuristic evaluation 3-5 experts in HCI view or interact with a prototype. – May vary from mock-ups and storyboards to a working system They use high-level heuristics as guidelines, and identify any problems they see. For example: – Does the interface use natural and simple dialog? – Does the interface provide good error messages? Designers compile and summarize all the problems and iterate. Where to get heuristics? – http://www.useit.com/papers/heuristic/ – http://www.asktog.com/basics/firstPrinciples.html Cognitive Walkthrough Assess learnability and usability through simulation of way novice users explore and become familiar with interactive system Experts walk through all steps in representative tasks, identifying trouble spots based on 4 questions • Will users be trying to produce whatever effect action has? • Will users be able to notice that the correct action is available? (is it visible) • Once found, will they know it’s the right one for desired effect? (is it correct) • Will users understand feedback after action? Advantages & Disadvantages Fast and cheap Does not need working system Detailed, careful examination that can cover entire interface Problems are subjective – are they really usability problems? Outcomes depend upon expertise and experience of the reviewers For more info: http://www.sis.uncc.edu/~richter/classe s/2006/6010/index.html or http://www.sis.uncc.edu/~clatulip/ITIS6 400/ITIS6400_Home.html Or take the course in the spring. Ethics of working with people Usability testing can be arduous; privacy is important Each person should know and understand what they are participating in: – what to expect, time commitments – what the potential risks are – how their information will be used Must be able to stop without danger or penalty All participants to be treated with respect Attribution Theory Studies why people believe that they succeeded or failed--themselves or outside factors (gender, age differences) Make sure participants do not feel that they did something wrong, that the errors are their problem Respecting your participants Be well prepared so participant’s time is not wasted Make sure they know you are testing software, not them Explain procedures without compromising results Make them aware they can quit anytime Make sure participant is comfortable Session should not be too long Maintain relaxed atmosphere Never indicate displeasure or anger State how session will help you improve system (“debriefing”) Don’t compromise privacy (never identify people, only show videos with explicit permission) IRB Institutional Review Board (IRB) Federal law governs procedures Reviews all research involving human (or animal) participants Safeguarding the participants, and thereby the researcher and university Not a science review (i.e., not to asess your research ideas); only safety & ethics http://www.research.uncc.edu/Comp/human.cfm Ethics Certification Ethics is not just common sense Training being standardized to ensure even and equal understanding of issues Go get your certification: due Sept. 18! http://www.research.uncc.edu/tutorial/index3.cfm IRB @ UNCC http://www.research.uncc.edu/comp/human.cfm On-line tutorial Guidelines Consent procedures and template forms Protocol application forms IRB Protocol 101 Training – http://www.research.uncc.edu/comp/human_trng.cfm – 9/10, 9/11, 9/12, 9/18, 9/20 from 6-7pm Assignments Scenario Your target users work in a hospital. Confidentiality of patient data cannot be compromised. Different employees have different levels of clearance within the one system that controls all of the patient records. There are a limited number of public workstations that are highly trafficked throughout the day. Current practice at the hospital is that one worker logs in and often many people with different levels of clearance work under that same account, even though they are not authorized to do so. Often, the workstation remains logged in between users, thus an unauthorized user could gain access to patient records. In addition, passwords change on a monthly basis so it is more convenient for the workers to just use the account that has already been logged in than try to recall their always changing password. Management insists that the passwords much change frequently to reduce the risk of a hacker viewing the confidential data. How to address security needs with passwords or other forms of authentication in this context? My current scenario Your target users are students and faculty doing studies in the usability lab. This lab is a room with two Novell computers with special usability recording software on them. Access to the lab is controlled by 49er card. All study personnel need to be able to access the study materials, but no one else should have access to those materials. Study materials include consent forms, questionnaires, and instructions to give study participants, both in digital and physical forms. Additionally, on the computer are the application and application data to be tested, as well as the digital recordings of the study. An external hard drive contains back up copies of all the recordings and application data. Most of the people in the lab will have Novell accounts, but not everyone. How can we provide shared access to the study materials? How can we prevent unauthorized people from getting access to the study materials and records? Usable Privacy & Security: An Introduction “weakest link property” – attackers only have to exploit one error or vulnerability Sociotechnical system – complex system of technologies and people/organizations So are people really the weakest link in security or privacy systems? How much is a self-fulfilling prophecy? Are security and usability competing goals? The product The technologies and processes put in place for security and privacy protection Why don’t they work? – Users are unable to behave as required How many accounts with passwords do you have? How many actual passwords do you have? – Users are unwilling to behave as required Do you create strong passwords all the time? User motivations Users underestimate their risk and the negative outcomes – Has anyone ever had a password compromised or misused? – how concerned are you about shoulder surfing for your passwords? – What could happen if someone could get into your email? Your blog? Your bank account? Users are not held accountable – Who makes sure you don’t write down your password? Who makes sure you don’t reuse passwords? Conflicts with social norms & self image – Have you ever shared a password with a friend/colleague? – Why wouldn’t you share your bank password with your spouse? Question: The real-world equivalent of good security is locking your home or car to protect your belongings. Yet those who follow good cybersecurity practices are perceives as “anal” or “paranoid.” Why the difference? The process The methods for creating the product. In your organization: – Who creates security policies and technologies for the employees? – Who creates the security policies and technologies for the customers/users? AEGIS – What are the benefits of this method? – What are its drawbacks? – Do the methods change if your users are non-technical? The panorama The context of the products, the larger environment Education – Teaching concepts and skills Training – Correct usage of security mechanisms through drills, monitoring, feedback, reinforcement – Should encompass all staff, not only those with immediate access to systems deemed at risk Attitudes – Role models What training/education have you had on good passwords? What training/education has your [favorite-non-technical-person] had? – What do you think they should have? – How could that be provided to them? Tog’s advice Achieving balance – User context and bad guy context – User task and authentication – Security and privacy “RingWall” metaphor – Castlekeep, ramparts, town wall, outside – Is this a reasonable metaphor? Question: Much of security and privacy concerns has more to do with where your information is, than where you are. Does Tog’s same desire for flexibility of privacy settings based on the user’s environment apply? Do the same metaphors apply?