1. Questionnaire Structured vs. semi-structured Pros of structured questionnaire Be able to collect unambiguous and easy to count answers High level of reported concordance with medical record data Cons of structured questionnaire Response choices may not be comprehensive Respondents may interpret the questions differently Scope for bias

2. Pros and Cons of Postal Self-administered Questionnaire Pros : Minimize social desirability and interviewer bias Suitable for covering large & geographically spread population Useful for sensitive topics Cheaper than interview and anonymous Cons: Only suitable for straightforward and simple questions Can’t probe for further details Less reliable due to can’t control over who completes it Low response rate Tend to underestimate respondents’ health problems

3. Pros and Cons of Face-to-face Interview Pros : Probe for responses, clarify ambiguities and misinterpretations Obtain detailed & in-depth information No literacy requirement for respondents Questions can be asked in predetermined order High response rate Cons: Expensive and time-consuming Potential for interviewer or interpreter bias Tend to under-report respondents’ health problems (mental)

4. Pros and Cons of Telephone Interview Pros : Save traveling time and cost Accurate reporting of health problems Cons: Not cheap and might time-consuming sample bias (under-represent low SES group w/o phone) Suitable for brief questionnaire and on non-sensitive topics only

5. Methods for Increasing Response Attach a covering letter Send an advance letter prior to the survey Offer incentives Translations and interpreters Appearance of the interviewer Call backs in personal interview Postal reminders Recalling in telephone survey

6. Factors related to Response Rate Saliency of topic perceived by respondents Length of questionnaire Ethnicity Occupation SES Location (rural vs. urban) Age

7. Missing Value Postal self-administered questionnaire Lengthy questionnaire Irrelevant questions to specific groups Methods deal with missing values Exclude them from analysis Imputation Assign to a specific coding (9 or 99)