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Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Questionnaire Design in an Outbreak Setting Dr Danilo Lo Fo Wong.

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Presentation on theme: "Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Questionnaire Design in an Outbreak Setting Dr Danilo Lo Fo Wong."— Presentation transcript:

1 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Questionnaire Design in an Outbreak Setting Dr Danilo Lo Fo Wong

2 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Tools for Information Gathering Direct measurement –A physician measuring a patient’s temperature as 40 o C with a thermometer Observations (what you saw and recorded) –Someone who felt hot Record review –Filling out data abstraction forms-whether a patient was reported with fever Interview - administering questionnaires –Did you have a fever? Y/N

3 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Pros and Cons to Interviewing Using Questionnaires vs. Other Tools Positives: –Obtain information otherwise not easily measurable –Gain a lot of data in a short period of time Negative: –Data can be inaccurate –Sometimes not useful based on wording –Validity of questions –Reliability of answers given

4 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 What is a Questionnaire? A list of questions (answered by a respondent) to generate an indirect and unobserved measure of the variables under investigation Design and administration of a questionnaire is a critical part of the study Poorly designed and administered questionnaires decrease the accuracy (validity) and the precision (reliability) of a measure

5 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Role of Questionnaires in Epidemiology Descriptive Study (e.g. cross-sectional) Surveillance (e.g. surveillance-report form) Evaluation of a system (e.g. laboratory testing among labs in a country) Analytic Study (e.g. assessing risk factors for S. Enteritidis) Outbreak investigation (e.g. hypothesis-generating)

6 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

7 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 1: Identify Initial Hypotheses Hypotheses often generated from a hypothesis generating questionnaire: –Interview a handful of cases –Often not long in length –Obtain information on illness onset, symptoms, laboratory-confirmation (if available), exposures –Opportunity to ask open-ended questions

8 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 1: Identify Initial Hypotheses Examples of hypotheses generated from hypothesis- generating questionnaires: –Eating tomatoes is associated with illness –The amount of milk consumed is associated with illness –Contact with a case is associated with illness Keep in mind: the investigator will test these hypotheses using a formal study questionnaire

9 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 What if the initial hypothesis-generating questionnaire produces no hypotheses?

10 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 1: Identify Initial Hypotheses Use a Trawling Questionnaire Very detailed, pre-made questionnaire Can be very long because of the number of questions asked May have to customize the questionnaire, adding questions based on information known Given to a handful of cases in the hopes of generating a hypothesis

11 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

12 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 2: Determine Type of Study Design Cohort Study Case-control Study Cross-sectional Nested Case-Control Study

13 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 2: Determine Type of Study Design Some factors to consider: Are cohorts available? Is there a common location, activity or event known at the beginning of the investigation? What resources are available to aid in the study? (example: membership lists, credit card receipts, etc.)

14 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

15 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Questionnaire Interview In PersonTelephone Postal Material is visual Establish trust Obtain detail Can clarify Takes time Cost- interviewer Inexpensive Trust, detail, clarify Who has telephones Privacy concerns Ratio: in/not in study Wide coverage Answer in own time Fairly inexpensive Ensures privacy Lessens interviewer effect Non-response rate an issue Requires literacy Follow up Fast to send out Those with Answer own time Inexpensive Ensures privacy Lessens interviewer effect Non-response rate an issue Responders different? Follow up Step 3. Determine how to administer questionnaire

16 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

17 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4: Plan the layout and design of the questionnaire a.Identify variables for the questionnaire b.Type of question and coding c.Formulate and phrase the questions d.Determine the sequence of questions

18 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4a. Identify Variables for the Questionnaire Identifying information and demographics –Respondent (Name, id number, etc...) –Age, sex, occupation etc.... Clinical information –Symptoms, Hospitalization, Outcome Exposure questions –Activities, Events, Food, Animal Contact, Travel Other –Laboratory information

19 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4a. Identify Variables for the Questionnaire Include variables to test hypotheses from hypothesis- generating interviews Include known risk factors Include biologically-plausible risk factors

20 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4b. Type of question and coding Consider type of question you ask and what data that question will generate Consider coding: –Ensure responses are easy to read and understand –Create response categories that are easy to record –Align responses so they are easy to record –Create response categories that are easy to analyze

21 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4b. Type of question and coding Unstructured: Open-ended questions –When there is interest in what information a subject will volunteer instead of asking specific responses Advantages: –Good when new ideas are sought –Traceback situations Disadvantages: –Not easy to record –Difficult to code responses, analyze data, and quantify results

22 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Unstructured Questions What did eat during the past week? ________________________ Example: Step 4b. Type of question and coding

23 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4b. Type of question and coding Structured: Question giving fixed response alternatives Advantages –Ease of use in the field and for data entry –Greater precision –Easy to quantify Disadvantages –Limits the variety and amount of data collected

24 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Dichotomous - two, analyzable categories e.g. Do you eat fish? Y N Nominal - more analyzable categories, not ordered e.g. What is the occupation of the patient? 1=store clerk 2=butcher 3= baker Ordinal-responses ordered e.g. Rank your favorite food –beet –tomato –Pepper e.g How many glasses did you drink yesterday? –1 glass –2-3 glasses –4 < glasses Step 4b. Type of question and coding Types of Structured Questions

25 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Create response categories that are easy to analyze Yes No DK Ref 1.Do you eat fish? Do you eat olives? Do you eat cheese? Step 4b. Type of question and coding

26 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 CaseControl Ate fish Did not eat fish need an outcome need an exposure What will be the easiest way to code the questions to analyze the data? Analytic Epidemiology: Keep in mind your future analysis………

27 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Ensure responses are easy to read and understand Name:__________ Date:____________ Age:_____________ Surname: __________ First name:_________ or Date: / / (dd/mm/yy) or Be specific in what you want to know Age: years months or Step 4b. Type of question and coding

28 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4c. Formulate and phrase the questions Simple, unbiased words As few words as possible Words that are culturally sensitive One concept per question Directed, non-leading questions Closed questions when possible Questions with skip patterns In creating questions, use: Did you eat lots of vegetables from the farm or market or grocery store such as carrots, potatoes, broccoli or cauliflower? Y N Do you think it might have been the eggs in the salad? Y N

29 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Consider the following: Is the question relevant? Has the question been tested before (used in other questionnaires?) Is the question known to be a valid measure of the problem under study?

30 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 4d. Determine sequence of questions/outline of questionnaire Identifying information Demographics Clinical information Exposures Other issues that may be relevant Ask questions about income, race, or other sensitive issues at the end - Example: “Do you have a history of drug use?” Y N

31 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

32 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 5: Pilot Test the Questionnaire Professionally pilot test the questionnaire –Time and money are issues Co-workers or friends can review the questionnaire –Free and maybe faster –Likely smaller group reviewing

33 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Issues to address: Wording and ease of understanding Unnecessary questions Response categories Unclear skip patterns Overall layout of questionnaire Step 5: Pilot Test the Questionnaire

34 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

35 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 6: Translation Best to address interviewees in their own language Investigator develops questionnaire in own language Translation into local language Back-translation (check) Interviewers should be fluent in the language of the interview

36 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

37 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Step 7: Train Interviewers Interviewers should be very familiar with questionnaire Training should include: –An Interviewer’s Manual –Log sheet system to keep track of who has been contacted

38 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 At the training, discuss : Initiating the survey Asking every question Allowing silence for responses Avoiding leading gestures or statements Avoiding finishing statements for respondent Clarifying appropriate use of probes for open ended questions Proper coding of responses Step 7: Train Interviewers

39 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Steps in Questionnaire Design in an Outbreak Setting 1.Identify initial hypotheses 2.Determine type of study design 3.Determine how to administer questionnaire 4.Plan the layout and design of the questionnaire 5.Pilot test 6.Translation (if necessary) 7.Train interviewers (if applicable) 8.Administer follow-up questionnaire if needed

40 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 May be administered in response to an interesting finding in data analysis that requires more attention Step 8. Administer follow-up questionnaire if needed

41 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 A good questionnaire takes time and effort to design Don’t underestimate this !! To Keep in Mind…….

42 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Acknowledgements Adapted from “Questionnaire Design” by Maire Connolly, Field Epidemiology Training Program, and “Foodborne Disease Outbreak Questionnaire Design”, Foodborne and Diarrheal Diseases Branch, CDC, Atlanta, Georgia, USA Katrina Kretsinger, Stephanie DeLong Kleinbaum, D. Logistic Regression: A Self-Learning Text, Springer-Verlag, New York, 1994.

43 Foodborne Outbreak Investigation, Hanoi, Vietnam 01 – 05 June 2009 Thank you for your attention


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