Questionnaires

contain closed questions (attitude scales) and open questions

pre- and post questionnaires obtain ratings on an issue before and after an design change

can be used to standardise attitude measurement of single subjects following direct observation

can be used to survey large user groups

Types of rating scales

Can you use the following edit commands?yes no don't know

duplicate

paste

A simple checklist

Multipoint checklist

Rate the usefulness of the duplicate command on the following scale?

very of no useful use

Likert Scale

statement of opinion to which the subject expresses their level of agreement

Computers can simplify complex problems

very much agree slightly neutral slightly disagree strongly

agree agree disagree disagree

Caution!

The help facility in system A is much better than the help facility in system B

very much agree slightly neutral slightly disagree stronglyagree agree disagree

disagree

what does 'strongly disagree' mean?

Semantic differential Scaleuses a series of bi-polar adjectives and obtains

ratings which respect to each

Rate the Beauxarts drawing package on the following dimensions

extremely quite slightly neutral slightly quite extremely easy

difficultclear

confusingfun dreary

Rank Order

Place the following commands in order of usefulness (rank the most useful as 1, the least useful as 4)

paste duplicate group clear

Do and Don'ts with Questionnaire evaluation do be clear about the information you want

to obtain don't risk subjects becoming demotivated don't be lazy do provide specific task reference for

questions don’t assume that responses will be positive do pilot the questionnaire first

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Planning and logistics of questionnaire design

Quantitative or qualitative? Legal requirements: the Data Protection Act Confidentiality and anonymity Sample size Volunteer respondents Identifying subject areas Determining appropriate length Typical time scale Main components of questionnaires

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Content of items Avoiding response set Components of attitudes Common types of faulty items

leading questions context effects double barelled questions vague and ambiguous terminology hidden assumptions social desirability

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Leading questions and context effects

Would you agree that the governments policies on health are unfair?

Item wordings should not contain value judgements

How many pints of beer did you drink last night? Think how the context of the study would

affect the response, say in a survey of young peoples life styles survey of health behaviour and heart disease

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Double barreled questions

Do you believe the training programme was a good one and effective in teaching you new skills?

avoid questions that involve multiple premises

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Vague and ambiguous terminology

How often do you clean your teeth? Frequently often infrequently never

what does ‘frequently’ mean? Give quantifiers to ensure all respondents

understand the same thing by the response categories

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Hidden assumptions, social desirability

When did you last borrow a video tape? Avoid hidden assumptions - what are

these?

Do you ever give to charity? May lead to a positive response as

otherwise something negative about the respondent is being conveyed

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User diaries Used with early releases of complete systems People use system as part of their normal work and

keep a log of the tasks they have used the system for and whether or not they were successful in using the system

Has the advantage of using real tasks not contrived standard tasks

Requires that the system is capable of supporting enough tasks to be useful to the person doing the evaluation

Requires input from the evaluator to maintain the person’s motivation to keep using the diary

Observation and monitoring usage

User trials direct and indirect observation verbal protocolls Collecting user opinions

User diaries over period of extended use Surveys Software logging

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User trials - duration Aimed at observing people who are typically of the

intended user group using the interface (often a prototype)

People are usually volunteers – this limits the time available for each trial – serious constraint on what can be done

How much of your time would you give to help someone test a piece of software?

Assume a total trial length of 30 – 45 minutes – this has to include introduction, demonstration, data collection and de-brief

If subjects are paid then longer trials are possible

User Trials: structured tasks One approach is to give subjects a series of

standard tasks to complete using a prototype observe subject completing tasks under

standardised conditions data collection aimed at ensuring that qualitative

descriptions of problems during task completion are captured

Intention is to see whether different people encounter similar problems when using the interface

what problems are likely to arise in data recording?

Standard tasks in user trials structure tasks into incremental difficulty

(easy ones first) have a clear policy on subject becoming

stuck and providing help have a reason for including each task (avoid

unnecessary duplication) ensure (all) functional areas of interface

usage are covered ensure tasks of sufficient complexity are

included

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Example of standard tasks ‘Find the time of the latest train service leaving

Leicester that I can take next Tuesday to arrive in Dundee before 8.00 pm’

‘Find the cost of a return ticket for 2 adults and 2 children for the journey from Leicester to Bristol with no discounts such as saver or supersaver’

‘Find how many copies of Preece ‘Human-Computer Interaction’ the library currently holds’

Note: each task has a definite end point – the user can provide the answer to the question, which is either correct or incorrect

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Unstructured user trials Another approach to user trials is to ask the user

to browse through information – more appropriate for web-sites or multimedia presentations

Browsing behaviour is directed by the user’s interest rather than being asked to retrieve a specific piece of information

No guarantee that subject visits all parts of the application or site – how much of the site they visit is often useful information in itself

Requires that subject is actually interested in the application or site

Indirect observation - video enables post-session debriefing 'talk-through'

(post-event protocolls) enables quantitative data to be extracted -

e.g. part task timings serves as a diary and visual record of

problems usually very time consuming to analyse usability laboratories – facilities to administer

standard tasks, record data and analyse these

Verbal protocols

means of enhancing direct observations user articulates what they are thinking during

task completion (think-aloud protocols) but…

doing this can alter normal behaviour subject likely to stop when undertaking complex

cognitive activities user may rationalise behaviour in post-event

protocols get subjects working in pairs - co-discovery can

overcome some of these problems.