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Survey Experiment Modalities. Some Pros and Cons of Differing Sampling Sources and Methods. Matthew A. Baum Harvard University & Leonie Huddy Stonybrook University. Outline. Review of prominent Internet players Amazon Mechanical Turk Knowledge Networks Yougov/Polimetrix
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Survey Experiment Modalities Some Pros and Cons of Differing Sampling Sources and Methods Matthew A. Baum Harvard University & Leonie Huddy Stonybrook University
Outline • Review of prominent Internet players • Amazon Mechanical Turk • Knowledge Networks • Yougov/Polimetrix • SurveyMonkey Audience • Comparing survey modalities • USA vs. Swedish Phone/Internet Usage Statistics • Conclusions
Amazon Mechanical Turk (AMT) • Overview • Began in 2005 • “Workers” sign up to participate in tasks for pay (called “Human Intelligence Tasks”, or “HITs”) • Global workforce (~100,000 workers) • Salary: ~$3-$8/hour (maybe $10/hr for high-experience workers) • “Requestors recruit “workers” on internal message board describing task • Can specify “qualifications” for workers (e.g., experience, quality ratings, nationality, etc.) • 10% fee to Amazon • AMT provides survey building tools, or Requestors can include links to external surveys • HITs range from 1-second marketing surveys (“Rate appeal of this photo on 1-10 scale”) to elaborate 30+ minute experimental surveys
Amazon Mechanical Turk (AMT) Effects of Compensation Amount and Task Length on Participation Rates (Submitted Surveys per Hour of Posting Time) Source: Buhrmester, Kwang, and Gosling (2011) • My AMT Experience: • paid $1.00 per completed HIT for ~22 minute survey • Listed as “News and Politics Survey” • Received 1933 completed surveys in ~one month • rapidly diminishing returns • 1825 valid responses
Amazon Mechanical Turk (AMT) Demographics Buhrmester, Kwang, and Gosling (2011) Paolacci, Chandler, and Ipeirotis (2010)
Amazon Mechanical Turk (AMT) Demographics
Follow-Up Survey • Contacted all 1825 workers who completed valid HITs in original survey approximately 4 months later • Offered $.50 for ~12 minute survey • 426 valid responses (24%) 2nd batch of invites
Tradeoffs Source: Paolacci, Chandler, & Ipeirotis (2010)
Some Conclusions re AMT • “Our analyses of demographic characteristics suggest that MTurk participants are at least as diverse and more representative of noncollege populations than those of typical Internet and traditional samples. Most important, we found that the quality of data provided by MTurk met or exceeded the psychometric standards associated with published research.” • Buhrmester et al. (2011) • “Our theoretical discussion and empirical findings suggest that experimenters should consider Mechanical Turk as a viable alternative for data collection.” • Paolacci et al. (2010)
Knowledge Networks • 2007 Survey (via TESS) • Participants recruited via residential address searches • Respond online (Internet access provided to recruits who don’t have it) • Pretty good samples, but imperfect (selection effects not completely purged) and expensive • Demographics
Recent (2012) KN Proposal • Design: 4-wave study, longitudinal sample, all waves occurring within 1 year • Pretest: N=25 interviews each wave • Sample: General population adults, age 18+, English-language survey-takers • Number of completed interviews: N=2,000 wave 1, with about 70%-80% of wave 1 respondents completing each of the later waves • Median survey length: 20 minutes each wave • Multimedia/graphics: None • Incentives: $5 for each of waves 1-3, $10 for wave 4 • KN will provide standard deliverables (self-documented data file with all the survey data, general demographic profile data, and field report documenting all sampling and data collection procedures, codebook, and panel recruitment methodology) • Price: $255,550 (No, that’s not a typo!)
Yougov/Polimetrix • Opt-in sampling • Random draw from target population matched with most comparable available panelists to create representative population samples • Demographics + attitudinal/behavioral factors • *Notes: • Overweights battleground states 2-fold. • Demo weights based on age, race, gender, educ, marital status, kids, income, state, metro area, employment, citizenship • Attitude/Behavior weights based on religion, church attendance, evangelical status, news interest, PID, ideology.
Comparing Modalities: KN vs. Polimetrix vs. Natural Survey: Barabas & Jerit (2010)
Polimetrix vs. Pew vs. NES (Partisan Distribution) Source: Hill, Lo Vavreck & Zaller (2007)
Polimetrix vs. Pew vs. NES (Ideologial Distribution) Source: Hill, Lo Vavreck & Zaller (2007)
Demographic Comparisons Source: Hill, Lo Vavreck & Zaller (2007)
Comparing Modalities: KN vs. Polimetrix vs. Natural Survey: Barabas & Jerit (2010) Conclusions: “The results presented here should be encouraging to anyone devoted to the scientific study of politics because they suggest that what occurs in survey experiments resembles what takes place in the real world.” “Although there was a discrepancy between the size of survey treatment effects and the general population in our natural experiment, we observed correspondence exactly where one would expect to find it—among those who were most likely to be exposed to media messages about the two government announcements.”
SurveyMonkey Audience • New enterprise for SM • still figuring it out! • Recruit participants from survey respondents • Currently U.S. only, but likely to expand • $3 per finished response; $5 for rush project (3 business days) • Custom create demographic profiles • Gender, age, income, location, education, race, industry of employment, job function, marital status, employment status, home ownership, vehicle ownership, smartphone ownership, exercise habits. • No political attitude selectors yet (though I’ve lobbied them!) • Similar to Polimetrix, except don’t start with random draw from population • Much less expensive!
AAPOR 2010 Task Force on Online Panels • Focus on nonprobability samples • Informative, but inconclusive… • Conclusions • If research objective includes accurate estimate of population values, avoid nonprobability online panels. • Results differ significantly from probability-based methods (like RDD telephone) on range of behaviors and attitudes, with latter being more accurate. • Nonprobability online panels sometimes appropriate, when precise estimates of population values not critical • More research needed on evaluating and testing techniques used across disciplines to make population inferences from nonprobability samples.
Ansolabehere & Schaffner (2011) • Comparison of Survey Modalities • 3-mode study conducted in 2010 • Opt-in Internet panel • Live telephone interviews (using national RDD sample of landlines and cell phones) • Mail (using national sample of residential addresses)
Ansolabehere & Schaffner (2011) *mail recruits who took survey online
Ansolabehere & Schaffner (2011) • Non-validatable Political Point Estimate Comparison, by Mode • Includes State of Economy, • Approval of/Support for Obama, Congress, R’s Member, Abortion, Affirmative Action, Gay Marriage, Investing Social Security, Tax over $200k, Cut Spending, Government • Right and Wrong • Voting Method • Religious and/or Political Contributions • Political Knowledge • News Source Weighted proportions of respondents in each category, excluding DK.
Ansolabehere & Schaffner (2011) • Small (“negligible”) differences across modes • Except…Internet respondents more politically knowledgeable & made more political contributions • Mail costs 5 times more than Internet & twice as much as phone • Internet half as costly as phone and faster turnaround • Differences from other studies that found Internet samples less valid than phone samples attributed to (1) more Internet users than 5+ years ago when prior data samples collected, and (2) advances in “science of constructing, matching and weighting opt-in Internet panels” • Conclusion: “...an opt-in Internet survey produced by a respected firm can produce results that are as accurate as those generated by a quality telephone poll and that these modes will produce few, if any, differences in the types of conclusions researchers and practitioners will draw in the realm of American public opinion.”
Media Access, Sweden vs. USA U.S. Telephone Ownership
Swedish Phone Use by Age Source: Axelsson (2010)
Why Persistent Mobile Phone & Internet Usage Gaps? Income Inequality: USA vs. Sweden in 2011
Effects of Income on Internet Usage in U.S. U.S. has more of these folks
What Do Data Tell Us? • Swedes more likely to be online in 2010 (by ~14 percentage points), and make greater use of Internet • But, similar in fixed broadband and landline usage • More likely to use mobile phones • But similar in volume of mobile calls sent and received • Moral of story? Infrastructure looks, if anything, LESS hospitable to probability sampling in Sweden than in USA • So, if RDD today works better in Sweden for generating probability samples, reason seems likely to have more to do with attitudes toward surveys than infrastructure
Conclusions • Opt-in Internet samples here to stay • Cheaper (by a lot!) • Faster (by a fair amount…) • Primary competitor (RDD phone surveys) increasingly difficult • 14% of adults “unreachable” in Sweden? • Estimated 25% of U.S. households cell only in 2010. • “Unreachable”: ~13% (AAPOR 2010); others say more • Open up new possibilities • E.g., cross-national samples/panels • Most current evidence suggests that with current matching and weighting techniques, Opt-in Internet samples can be representative of target populations