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Comprehensive Survey Design and Sampling Techniques for Accurate Data Collection

Explore methods to design and implement surveys effectively, determine sample accuracy, and calculate confidence intervals. Learn about various survey modes and their advantages and disadvantages.

paki-garrett
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Comprehensive Survey Design and Sampling Techniques for Accurate Data Collection

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  1. Agenda • Review assignment three • More on sampling • Survey design • Implementing surveys

  2. More on sampling • How do we determine the accuracy of sample estimates? • How do we determine how large a sample we should draw?

  3. Respondent Age 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30

  4. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10

  5. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9

  6. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9 Standard Deviation: __ s = s2  =  8.62 = 2.94

  7. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9 Standard Deviation: __ s = s2  =  8.62 = 2.94 Standard Error: s 2.94 s.e. = ___ = = .93  N  10

  8. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9 Standard Deviation: __ s = s2  =  8.62 = 2.94 Standard Error: s 2.94 s.e. = ___ = = .93  N  10

  9. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9 Standard Deviation: __ s = s2  =  8.62 = 2.94 Standard Error: s 2.94 s.e. = ___ = = .93  N  10 95% Confidence Interval: 24.2 +/- (1.96 x .93) = 24.2 +/- 1.82 = 22.4 to 26.0

  10. Respondent Age Mean: n i=1  xi 1 2 3 4 5 6 7 8 9 10 20 22 22 23 24 24 24 25 28 30 (20+22+22+23 … +30) 242 x = = = = 24.2 N 10 10 Variance: n i=1  (xi – x)2 s2= = (20-24.2)2 + (22-24.2)2 … 77.6 = = 8.62 N-1 10 - 1 9 Standard Deviation: __ s = s2  =  8.62 = 2.94 Standard Error: s 2.94 s.e. = ___ = = .93  N  10 95% Confidence Interval: 24.2 +/- (1.96 x .93) = 24.2 +/- 1.82 = 22.4 to 26.0

  11. Results of 100 Samples of N = 500 25 20 15 10 5 Std. Dev = 2.39 Mean = 45 0 N = 100.00 25 35 45 55 65 75 SAMPL500 The standard deviation of all sample estimates of a given mean is the is the STANDARD ERROR of the mean The CONFIDENCE INTERVAL -- plus or minus 2 S.E.s -- is the range within which 95 percent of all sample means of a given size will fall

  12. Survey designs • Mail • Telephone • Face to Face • Electronic

  13. Mail surveys • Advantages • Cost effective • Minimizes social desirability effects • Permits complex question formats • Disadvantages • Coverage and response-rate problems • Dillman’s Total Design Method can help • No direct monitoring of interview

  14. Telephone surveys • Advantages • Cost effective • Interviews can be monitored • Generally good coverage (with RDD methods) • CATI standardizes and eases data entry • Disadvantages • Phone response rates may be declining • Long phone interviews can be burdensome • Some complex question formats difficult

  15. Face-to-face surveys • Advantages • Interviewers can insure higher data quality • Can produce high response rates • CAPI standardizes and eases data entry • Disadvantages • Very expensive • Interviewer effects • Requires very well trained field interviewers

  16. Electronic surveys • E-mail and Web surveys • Advantages • Very cost effective • Permits very complex question formats • Automatic data entry • Disadvantages • Often involve severe coverage problems • No direct monitoring of interview

  17. Mixed-mode designs • Mail or E-mail with phone follow-ups • Motivated by desire to increase response rates • Introduces mode-of-interview bias • May confound respondent accessibility with mode-of-interview • Mode-effect problems can be reduced (though usually not eliminated) though careful design choices

  18. Design considerations • Coverage issues • Sampling design • Sample non-response

  19. Coverage issues • Problematic commercial sampling pools • Missing eligible sample elements • Unlisted phone numbers • Mobile respondents • Selection of respondents within households • Enumeration of household (Kish method) • Last-birthday method

  20. Sampling design • Simple random samples not so simple! • RDD telephone surveys need to be weighted for number of phones per household • Cluster samples • Select from primary sampling units (e.g., metro areas); then secondary units (census tracts, households, etc.) • The smaller the number of units sampled at each stage, the larger the sample variances (and standard errors)

  21. Sample nonresponse • Response rate: Completed interviews -------------------------------------------------------------- All respondents drawn in sample • Rate depends upon • Non-contacts • Refusals • Breakoffs • High response rates require persistence • Callbacks and refusal conversion

  22. For Tuesday • Archival research and secondary analysis • Schutt, Ch. 11 • Begin thinking about your group research designs • Group workshops on Thursday

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