This article compares online recruitment via Facebook, Mechanical Turk (MTurk), and Qualtrics panels across two countries: India and the United States.

Data & Methods Comparison: The study analyzed over 7300 respondents—1000 or more from each platform/country combination. Researchers compared these samples against nationally representative benchmarks in terms of demographics, political attitudes, knowledge levels, cooperation rates, and experimental replication quality.

Key Findings:

* In the United States: MTurk provides cheapest/fastest recruitment; Qualtrics yields most demographically/politically representative sample; Facebook facilitates targeted sampling.

* In India: Samples were found less representative overall, despite broad geographical coverage via Facebook. However, online convenience samples still offered valid inferences regarding partisanship moderation.

Why It Matters: While these platforms can be useful tools for research design and may yield defensible results on some topics like partisan effects, they often produce unrepresentative samples that question the external validity of findings.