1 Sampling Methods for Web and Surveys Associate Professor Ron Fricker Naval Postgraduate School Monterey, California

2 Today Anyone Can “Survey” for Little Cost

3 Internet-based Surveys and Sampling Focus is on survey data collection to support statistical inference Internet-based surveys often conducted via multiple media and mixed (survey) mode –“Contact mode” – respondent contact medium –“Survey or response mode” – survey medium –“Follow-up mode” – non-response follow-up medium

4 Bigger Samples Are Not Always Better When conducting Internet-based surveys, temptation is to (attempt to) survey everyone. Why not? It’s cheap and easy… Example: Survey2000 –Goal: Quantify how often people have moved, what role they play in their communities, and how geography has shaped their tastes in food, music, and literature More than 80,000 surveys initiated and 50,000+ completed

5 Types of Internet-based Surveys

6 Internet Surveys Pose Significant Challenges for General Populations Internet users do not reflect the general population –Frame and coverage bias Very hard to impossible to generate a sampling frame –There is no master list of addresses Recruiting respondents via the web can introduce bias Unethical/illegal to solicit survey participation via (spam)

7 Unsolicited is Spam

8 Problems Mitigated for Some Populations Internet-based surveys within individual organizations often easier –List of addresses or common address syntax often available –No problem with as spam But issues can remain –How complete is the address list? –Do all respondents have access to the Internet/ ? –Non-response issues and bias

9 Summary