Date post: | 29-May-2015 |
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Sampling for Internet Research
Carma Research ModuleJeff Stanton
May 15-17, 2008 Internet Data Collection Methods (Day 2-2)
Universe, Population, Frame
Universe: U.S. Residents, 18+
Population: Males, 18+
Sampling Frame
…
May 15-17, 2008 Internet Data Collection Methods (Day 2-3)
Universe, Population, Frame, Sample
Universe: U.S. Residents, 18+
Population: Males, 18+
Sampling Frame
…
Sample
Malhotra, N. K. (1999). Marketing research: An applied orientation. (International 3rd edition). London: Prentice Hall.
May 15-17, 2008 Internet Data Collection Methods (Day 2-4)
Multiple Sources of Error(http://www.idready.org/courses/2005/spring/survey_SamplingFrames.pdf)
May 15-17, 2008 Internet Data Collection Methods (Day 2-5)
Sampling for Internet-Based Studies
Final Sample
OpenRecruitment
How to find, buy, or
build this list?
Email Invitation
May 15-17, 2008 Internet Data Collection Methods (Day 2-6)
Probability vs. Non-Probability
Superior Statistical“Projectability”
RDD – May provide truly random sample
Intra-Org Census as Sampling Frame
Limited or no Statistical “Projectability”
Assumes triangulationis required
Generalizability basedin part on theory foundation
May 15-17, 2008 Internet Data Collection Methods (Day 2-7)
Two types of Non-Probability Sampling
•Non-purposive–Convenience sampling–Open recruitment–Student samples in place of actual population–Snowball or chain (can also be purposive)
•Purposive–Expert, Quota, Politically important–Heterogeneity, Extreme/deviant, maximum variation, intensity–Homogeneity, modal instance, critical case, criterion, –Theory-based, disconfirming
Patton, M. Q. (1990). Qualitative evaluation and research methods (2nd ed.). Newbury Park, CA: Sage Publications.
May 15-17, 2008 Internet Data Collection Methods (Day 2-8)
Internet Sources of Samples
•Non-purposive–Email harvesting–Snowball, chain emails, or IM-Buddy lists–Banner ads–Site-based polls–Site-based links–Class rosters–Social networking sites
•Purposive–Organizational membership lists–Listservs of interest groups or professional organizations–Purchased sample frames–Standing panels–Amazon MechTurk
Amazon Mechanical Turk
Some pundits have commented that you can pay $0.03 per survey question. Responses come quickly: more than one response per minute in some cases.
Mturk Has Built-in Survey Capability
Mturk Provides Quick Responses
Internet Data Collection Methods (Day 2-12)
Criticisms of Internet Samples
Internet users per 100 people
Digital Divide: respondents from different communities have differing access to necessary tools
Non-sampled respondents providing responses
Sampled respondents providing bogus responses due to lack of proctoring
Amorphous sampling frame (e.g., due to posting an open link)
May 15-17, 2008 Internet Data Collection Methods (Day 2-13)
A response to these problems:Mixed Mode Design
• Telephone response rates have dropped from the 70-80% in the mid-20th century to less than 40%; mail response rates have always been low; Internet response rates have declined
• Solution: Combine mail, phone, Internet, and other modes
• Use best available sampling for each mode
• Instrument design presents another challenge: Uni-mode or mode specific
May 15-17, 2008 Internet Data Collection Methods (Day 2-14)
Preferred Strategy: Mixed Mode Sampling
Start with Theory
Answer: Who,When, Why
Develop MultipleSample Sources and
Research Modes
Sampling Frame 1: Mail or Other Sample
Sampling Frame 2: Internet Sample
KnownPopulation
Values
Triangulate:Calibrate &
Compare