2004 Public Health Training and Information Network (PHTIN) Series

1. 2004 Public Health Training and Information Network (PHTIN) Series

2. Site Sign-in Sheet Please mail or fax your site’s sign-in sheet to: Linda White NC Office of Public Health Preparedness and Response Cooper Building 1902 Mail Service Center Raleigh, NC 27699 FAX: (919) 715 - 2246

3. Outbreak Investigation Methods From Mystery to Mastery

5. 2004 PHTIN Training Development Team Pia MacDonald, PhD, MPH - Director, NCCPHP Jennifer Horney, MPH - Director, Training and Education, NCCPHP Anjum Hajat, MPH – Epidemiologist, NCCPHP Penny Padgett, PhD, MPH – Epidemiologist and Surveillance Officer, NCCPHP Amy Nelson, PhD - Consultant Sarah Pfau, MPH - Consultant Amy Sayle, PhD, MPH - Consultant Michelle Torok, MPH - Doctoral Candidate Drew Voetsch, MPH - Doctoral Candidate Aaron Wendelboe, MSPH - Doctoral student

6. Future PHTIN Sessions September 14th. . . . . . .“Designing Questionnaires” October 12th. . . . . . . . . “Analyzing Data” December 14th. . . . . . . “Risk Communication” Each session will be on a Tuesday from 10:00 am - 12:00 pm (with time for discussion)

7. Session I – VI Slides After the airing of each session, NCCPHP will post PHTIN Outbreak Investigation Methods series slides on the following two web sites: NCCPHP Training web site: http://www.sph.unc.edu/nccphp/training/index.html North Carolina Division of Public Health, Office of Public Health Preparedness and Response http://www.epi.state.nc.us/epi/phpr/

8. Session III “Interviewing Techniques”

9. Today’s Presenters Anjum Hajat, MPH Epidemiologist, NC Center for Public Health Preparedness Martha Salyers, MD, MPH Team Leader, Public Health Regional Surveillance Team 6, Buncombe County Health Center Sarah Pfau, MPH Moderator

10. “Interviewing Techniques” Learning Objectives Upon completion of this session, you will: • Recognize the interrelatedness of interview techniques and questionnaire design • Understand key survey research terms • Understand the advantages and disadvantages of face-to-face and telephone interview methods

11. Learning Objectives (cont’d.) • Understand the advantages and disadvantages of mail and web based survey implementation • Know what to cover in interviewer training • Recognize good interview techniques • Understand confidentiality concerns from the perspectives of both the respondent and the outbreak investigation

12. Basic Steps of an Outbreak Investigation • Verify the diagnosis and confirm the outbreak • Define a case and conduct case finding • Tabulate and orient data: time, place, person • Take immediate control measures • Formulate and test hypothesis • Plan and execute additional studies • Implement and evaluate control measures • Communicate findings

13. Interviewing Techniques Introduction

14. Introduction • The role of interviews in outbreak investigations • Types of interviewing methods • Interrelatedness of interview method and questionnaire design • Key survey research concepts • Sampling • Response rates

15. Role of Interviews in Outbreak Investigations Primary purpose: data collection • Case identification • Risk factor identification • Hypothesis generation

16. Interviewing Methods • Interviewer Administered • Face-to-face • Telephone • Self Administered • Mail-out • Email • Web-based • Combination of 1 and 2

17. Questionnaire Design Interview Method Influenced by: • Length and format of questionnaire • Question types used in a survey • Cost considerations for survey implementation

18. Questionnaire Design September 14th PHTIN Session: “Designing Questionnaires”

19. Sampling

20. Sampling Sampling is the systematic selection of a portion of the larger source population. A sample should be representative of the larger source population.

21. Sampling Source Pop: Students (12,000) Sampled pop (150 students)

22. Sampling Why Sample? Because it is more efficient – saves time and money!

23. Sampling Sample size Is the purpose of the study to determine the source of the outbreak? • A small number of cases and controls can reveal risk factors for infection. Is the purpose of the study to determine the number of persons who become sick over a specific period of time [attack rate]? • A cohort study would require a larger sample.

24. Sampling Types of Sampling Simple Random Sample (SRS) Randomly select persons to participate in study. There are many variations of SRS. Convenience Sample Choose those individuals who are easily accessible.

25. Sampling Problems with Convenience Sampling • Based on subjective judgment • Cases may or may not be representative of the total population • May lead to biased results

26. Sampling Additional Resources: http://www.sph.unc.edu/nccphp/training/all_trainings/at_sampl.htm • “Sampling Case Studies” • “Survey Sampling: Precision, Sample Size, and Conducting a Survey” • “Survey Sampling Terminology and Methods”

27. Response Rates

28. Response Rates Response rates measure the percentage of your sample that has participated in your survey. Example: Using the campus directory, you email a survey to a random sample of 100 freshmen. 40 of those students complete the survey and return it electronically. Your response rate is 40%.

29. Response Rates High response rates ensure that survey data are representative of the source population, and that results will be valid.

30. Response Rates Types of Non-response • Non-contact: No one at home • Refusal to participate • Inability to participate (due to language barrier or physical or mental condition)

31. Response Rates What is an average response rate?

32. Response Rates Determining Response Rates Refer to the American Association of Public Opinion Research website: www.aapor.org • Link to the document titled, “Standard definitions” from the home page.

33. Interviewer AdministeredData Collection Considerations

34. Interviewer Administered Data Collection • Advantages and disadvantages of face-to-face interviews • Advantages and disadvantages of telephone interviews • Computer Assisted Interviews • PHRST Region 5 PDA initiative

35. Interviewing Methods • Interviewer Administered • Face-to-face • Telephone

36. Face-to-Face Interview Advantages: • Higher response rate • Longer survey instrument • Can have more complex skip patterns • More accurate recording of responses • Less item non-response • Appropriate for hard to reach populations (e.g., illiterate, institutionalized)

37. Face-to-Face Interview Disadvantages: • Costly • Potential for interviewer error • Less anonymous than self-administered • Participants less inclined to be honest

38. Telephone Interview Advantages: • Less costly than face-to-face • Higher response rates than mailed • Quicker access to participants • Supervision of interviewers feasible • Can collect more sensitive information • Survey design can be more efficient

39. Telephone Interview Disadvantages: • Lower response rates than face-to-face • Shorter questionnaires used • Unable to capture important visual information (e.g., rash, working conditions) • Under-coverage (e.g., population without phones)

40. Percentage of Households with No Telephone Service by County, NC Data source: 2000 U.S. Census

41. Computer Assisted Interviewing (CAI) • CATI – Telephone • CAPI – Personal • ACASI – Audio

42. CAPI Example:PHRST Region 5 In the PHRST Region 5, NC public health professionals are training to use PDAs* for outbreak investigation and rapid needs assessment face-to-face interviews. * PDA: Personal Digital Assistant, also sometimes called hand-held computers, palmtops, and pocket computers To learn more about this technology initiative, please contact Steve Ramsey at sramsey@co.guilford.nc.us

43. CAPI Example: PHRST Region 5

44. Self AdministeredData Collection Considerations

45. Self-administeredData Collection • Advantages and disadvantages of mailed questionnaires • Advantages and disadvantages of Web-based questionnaires

46. Interviewing Methods • Self Administered • Mail-out • Email / Web-based

47. Mailed Questionnaire Advantages: • More anonymous • May collect more honest responses • No interviewer error • Less expensive • Respondent has more time to think about question

48. Mailed Questionnaire Disadvantages: • Questionnaire must be simple • Higher item non-response • Lower response rate • Data collection takes more time • Sample population must be literate • Coverage / frame deficiencies

49. Web-based Questionnaire Advantages: • Among some populations, most people may have access to the Web / email • Inexpensive and fast • No data entry required • Improves data quality • Many vendors send data in a variety of formats

50. Web-based Questionnaire For a list of vendors that provide Web-based survey tools, please visit: http://www.surveymonkey.com/Pricing.asp