Collecting the Data: Nonsampling Errors and Response Rate Calculation

1. Collecting the Data: Nonsampling Errors and Response Rate Calculation Chapter 18

2. SLIDE 18-1 Tentative Distribution of Sample Means for Various Research Plans 1 2 _ x 4 3 _ x m True A: n=50; Ask students for overall grade point average (GPA) B: n=50; Obtain GPAs using registrar’s records C: n=300; Ask students for overall GPA D: n=300; Obtain GPAs using registrar’s records

3. Noncoverage Errors Nonobservation Errors Nonresponse Errors NONSAMPLING ERRORS SLIDE 18-2 Overview of Nonsampling Errors Response Errors Observation Errors Office Errors

4. SLIDE 18-3 Three Methods for Diagnosing Nonresponse Error • Contact a sample of nonrespondents • Compare respondent demographics against known demographics of population • Conduct an analysis of late responders vs. early responders

5. SLIDE 18-4 Identifying Potential Response Errors • Does the respondent understand the question? • Does the respondent know the answer to the question? • Is the respondent willing to provide the true answer to the question? • Is the wording of the question or the situation in which it is asked likely to bias the response? Source: Weiers 1988

6. SLIDE 18-5 Total Error is the Key Sampling Error Noncoverage Error Nonresponse Error Response Error Office Error

7. # Usable Questionnaires Returned Response Rate = # Contact Attempted – # Bad Addresses or Fax Numbers Response Rate Calculation:Mail, E-mail, and FAX Surveys SLIDE 18-6

8. # Completed Interviews Response Rate = # Completed + # Refusals + # Not-at-Homes Interviews Response Rate Calculation: Telephone Surveys (No Eligibility Requirement) SLIDE 18-7

9. # Completed Interviews Response Rate = # Completed + E % [ # Refusals + # Not-at-Homes ] Interviews SLIDE 18-8 Response Rate Calculation: Telephone Surveys (With Eligibility Requirement) # Completed Interviews Eligibility (E) % = # Completed + # Ineligibles Interviews

10. Respondent interest in topic “Foot-in-the-door” Interviewer characteristics and training Guarantee of confidentiality or anonymity Pre-notification Personalization Sponsor disguise Response incentives Survey length Follow-up surveys SLIDE 18-9 Improving Response Rates