6. Recap of Conducting Surveys I Reasons for conducting a survey Issues in effective questionnaire design, data collection and analysis, and reporting Questionnaire design, especially measurement, content, and structure
8. Sample A subset of individuals within a population of interest Sampling is the act, process, or technique of selecting a suitable sample, or a representative part of a population for the purpose of determining parameters or characteristics of the whole population Goal of sampling: to be able to make inferences to the population in question
10. Sampling process Defining the population of concern Specifying a sampling frame, a set of items or events possible to measure Specifying a sampling method for selecting items or events from the frame Determining the sample size Implementing the sampling plan Sampling and data collecting Reviewing the sampling process
11. Define the population Definition: Entire universe of individuals who have characteristic of interest Examples: Residents of city, residents of county, library card holders, users, nonusers, visitors to library, computer lab users, program attendees
12. Sampling frame Definition: has a property that we can identify and can include in our sample Examples: telephone directory, city directory, patron database, attendance sheets, voter registration list, utility bill recipients, newspaper readers, random digit dialing (RDD)
13. Sampling methods Probability sampling: every individual has an equal chance of being selected Nonprobability sampling: some units in the population have no chance of selection or the probability of selection can’t be accurately determined
14. Sampling methods examples Probability Simple random Systematic Stratified Nonprobability Convenience Judgment Quota Snowball
15. Sampling example #1 Simple random Population: Patrons Frame: Patron database Method: Random number generator—in Excel: =RANDBETWEEN(num1,num2)
16. Sampling example #2 Systematic Population: City residents that have a listed land-line telephone Frame: Telephone directory Method: Randomly select a number n (ex., 20) or smaller, start there on the first page of the directory and select every nth (ex., 20th) entry
17. Sampling example #3 Convenience Population: Library visitors Frame: Anyone who approaches or passes by the reference desk Method: Stop as many people as possible
18. Population example Entire universe Population: Event attendees Distribute questionnaire to everyone in attendance
19. Sample size criteria Level of precision/sampling error (e.g., ±5 percent): range in which the true value of the population is estimated to be Confidence level: repeat sample values are normally distributed about the true value Degree of variability: heterogeneous populations require a larger sample size
32. Related topics NCompass Live archived sessions Conducting Surveys I: Introduction and Questionnaire Design – May 12, 2010 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9680 Presenting Data in Meaningful and Interesting Ways – Jan. 1, 2010 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9338 American Factfinder - Mining the U.S. Census for Information about Your Community – Dec. 9, 2009 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9297
33. Upcoming sessions Tech Talk with Michael Sauers – June 30 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9639 Conducting Surveys III: Analyzing Data and Reporting Methods – July 14 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9638 Communication--Getting the Word Out: Does your audience hear what you mean? – July 21 http://www.nlc.state.ne.us/scripts/training/eventshow.asp?ProgID=9238
34. Resources Survey Research Methods, 4th Ed., by Floyd Fowler http://www.statpac.com/surveys/sampling.htm http://www2.uiah.fi/projects/metodi/152.htm http://www.socialresearchmethods.net/kb/sampling.php http://nelearns.blogspot.com/2010/05/thing-37-engaging-your-users-with-polls.html http://www.techsoup.org/learningcenter/software/page10744.cfm http://www.techsoup.org/learningcenter/internet/page5048.cfm