Psychological Science on the Internet: Designing Web-Based Experiments From the Ground Up

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Psychological Science on the InternetDesigning
Web-Based Experiments From the Ground Up

• R. Chris Fraley
• University of Illinois at Urbana-Champaign

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Introduction

• During the last few years an increasing number of
  psychologists have begun to use the Internet to
  collect empirical data.
• The Internet has the potential to be useful for
  two reasons
• Integrated data management
• Whether you collect data from undergraduate
  subject pools, community samples, or elsewhere,
  you can use the same platform for research
  design, collecting data, providing feedback, and
  managing data.
• Open laboratory
• Participants can take part in your research any
  time of the day.
• If desired, you can open your lab doors to people
  from across the world.

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Our plan

• My objective today is to illustrate some of the
  research techniques that can be implemented using
  the Internet.
• Outline
• 1. What kinds of research can be done using the
  Internet?
• 2. How to obtain access to a web server.
• 3. How to create a basic HTML web page that can
  be used to collect data.
• 4. How to create Perl/CGI scripts to process and
  save those data.
• 5. How to do advanced things, such as randomize
  stimuli/questions, randomly assign people to
  conditions, and present items/stimuli on separate
  pages.
• 6. A discussion on ethics, sampling concerns, and
  informed consent.

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Part 1Basic concepts and what can be done
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How the Net Works

• Most web pages are written in a language called
  HTML (hypertext markup language).
• HTML files exist on a web server. When a person
  types in the URL for a specific file in his or
  her web browser, the person is essentially
  retrieving that pre-existing file from the web
  server.

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How the Net Works
web user types a URL into the browser
web server locates requested HTML file and sends
it to users computer
web user the browser renders the HTML file as a
web page
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Static vs. Dynamic Web Pages

• The obvious limitation of using HTML pages in
  this manner is that the users web experience is
  statiche or she will see the same page each time
  he or she goes to that address.
• It is possible, however, to program the server to
  deliver dynamic contentcontent that varies from
  one situation to the next or from one person to
  the next.
• This kind of interactivity is necessary in order
  to produce the kinds of web pages that allow for
  creative, complex research designs.

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Dynamic Web Programming and CGI

• This kind of interactivity can be accomplished by
  writing programs, called CGI scripts, that run on
  the web server.
• CGI scripts are often written in Perl, PHP, or
  other languages. (Ill expand on some technical
  details later.) What is important to note right
  now is that those languages are available for
  free and, with a bit of practice, are relatively
  easy to use.

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Dynamic Web Programming and CGI
web user types a URL into the browser

• web server
• locates requested CGI script.
• Performs the commands and creates a new HTML
  file.
• Sends HTML file to users computer

web user the browser renders the HTML file as a
web page
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What Can Be Done with CGI Scripts?

• By using CGI scripts, it is possible to
  accomplish a number of feats that are impossible
  using standard web pages.
• save data
• randomize the order of questions
• random assignment to conditions
• track participants over time
• implement complex branching patterns
• customize text and images
• create customized feedback for users
• Lets discuss some of these points in more
  detail.

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Automatically Save Responses to a Data File

• One of most time-consuming aspects of conducting
  paper-and-pencil research is data entry.
• It is easy to write CGI scripts that save the
  data automatically.
• save as a comma-delimited text file (that can be
  easily imported into SPSS or MS Excel)
• save directly into a database (such as MySQL)

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snapshot of a comma-delimited text file
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Provide Participants with Customized Feedback

• One of the most valuable features of conducting
  research over the Internet is that it provides
  you with a way to provide instant feedback to the
  research subject.
• plot the persons scores
• create bar charts or tables that summarize the
  data (e.g., means, SDs, correlations) from the
  broader sample automatically

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Substitution

• One of the perks of using dynamic programming is
  that it allows for substitution.
• In other words, you can take information that has
  been provided by the user (or computed by some
  other part of the script) and substitute that
  into the web page that is sent to the user.

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My wifes name has been substituted into the web
page, making the questions tailored to me.
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Randomization of Stimuli Order

• In most questionnaire-based research, it is not
  unusual for researchers to present questions in
  the same order for each research participant.
• In fact, many researchers who have placed their
  questionnaires on-line have followed this
  practice.

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Randomization of Stimuli Order

• There are obvious limitations of using the same
  presentation order for stimuli.
• Most importantly, there may be systematic order
  effects that impact responding.
• By randomizing the order in which items/stimuli
  are presented, it is possible to minimize these
  kinds of problems.
• It is possible to randomize the order of stimuli
  quite easily using a CGI script.

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Random Assignment to Conditions

• It is also possible to use these same
  randomization techniques to randomly assign
  participants to experimental conditions.
• Importantly, it is easy to implement this in a
  way that precludes research subjects from knowing
  that they are in but one of many possible cells
  of a research design.
• Example
• http//www.web-research-design.net/cgi-bin/APS2005
  /experiment1.pl

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Measure Response Times

• It is also possible to write CGI scripts that
  assess the amount of time that a user spends on a
  web page.

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Measure Response Times

• It is not advisable to assess response times for
  decisions that can be made within a few seconds
  (e.g., lexical decision tasks) because it can
  take up to three seconds for a simple HTML page
  to fully load.
• However, by using multimedia applications, such
  as Macromedias Flash, it is possible to assess
  response times at a more microscopic level.

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Measure Response Times

• Example lexical decision application
• http//www.web-research-design.net/APS2005/lexical
  decision.swf

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Use Complex Branching Patterns

• One limitation of paper-and-pencil questionnaires
  is that it is difficult for participants to
  follow complex branching operations.
• There may be certain questions that should be
  skipped if the participant is not married, for
  example.
• If you want to tailor the stimuli to a specific
  user (e.g., a persons ideographically unwanted
  traits), it is difficult to do so with a
  paper-based test.
• Again, CGI scripts can be used to implement these
  conditional patterns.

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Track Participants Over Time

• It is often desirable to follow a group of people
  across time to study continuity and change in
  attitudes, moods, behavior, and traits.
• The Internet provides a useful way to track data
  across time because people can
• (a) log-on at their convenience
• (b) all submissions can be time-stamped
  automatically by the web server
• (c) the persons progress can be easily tracked
  across multiple sessions

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Learning How to Conduct Research over the Internet

• How do you do this stuff?!

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Learning How to Conduct Research over the Internet

• The first thing to note is that these techniques
  are relatively easy to learneven if you have
  very little experience in programming.

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Learning How to Conduct Research over the Internet

• What you need
• a computer with an Internet connection (dial-up
  modem or high-speed)
• a web server
• Professional hosting sites (e.g. , Netfirms)
• Create your own (e.g., spare PC, Apache software)
• software that is freely available over the
  Internet
• text editor (e.g., EditPlus)

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Learning How to Conduct Research over the Internet

• There are a number of web sites available that
  provide tutorials on designing HTML and CGI
  files.
• HTML
• http//www.w3schools.com/html/
• CGI
• http//www.cgi101.com/class/
• http//hotwired.lycos.com/webmonkey/98/47/index2a.
  html
• Both HTML and CGI
• http//www.web-research-design.net/ Note You
  can download a ton of free research-relevant
  scripts at this site

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Learning How to Conduct Research over the Internet

• There are also some useful books.

Guilford Press
Prentice Hall
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Learning How to Conduct Research over the Internet

• Finally, there are a number of professional
  services for hire that can design web studies for
  you.
• Knowledge Networks
• http//www.knowledgenetworks.com/
• Survey Monkey
• http//www.surveymonkey.com/

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