Faculdade de Medicina da Universidade do Porto Curso de Mestrado Integrado em Medicina 2010/2011

1. Faculdade de Medicina da Universidade do PortoCurso de Mestrado Integrado em Medicina2010/2011 http://jpn.icicom.up.pt/imagens/up/up_fmedicina.jpg INTRODUÇÃO À MEDICINA II TURMA 21 REGENTE: Prof Dr. Altamiro Costa Pereira PROFESSORA E ASSISTENTE: ProfDrª. Cristina Santos e Luís Pinto

2. Biases in questionnaire construction: how much do they influence the answers given?

3. Types of errors Affect questionnaires’ precision Random Errors Related to the variability inherent to a phenomenon that is being measured[1] Systematic Errors Affect questionnaires’ validity Related to the wrong association between an exposure and a certain effect [1] Commonly known as “biases” M. Delgado-Rodríguez and J Llorca, Bias, J. Epidemiol. Community Health 2004;58;635-641

4. Description of biases in literature M. Delgado-Rodríguez and J Llorca, Bias, J. Epidemiol. Community Health 2004;58;635-641 Bernard C.K. Choi and Anita W.P. Pak. A Catalog of Biases in Questionnaires. Preventing Chronic Diseases. 2005; 1; 13

5. Described biases Question Design

6. Described biases Administration of questionnaire

7. Described biases Questionnaire Design

8. Research Question http://static4.depositphotos.com/1000423/471/i/110/depositphotos_4715431-3D-man-with-question-mark.jpg Do these so called ‘biases’ really influence the answers given in questionnaires?

9. Aims • Check if the way we change a normal question influences the given answers in general. • Be able to sort out at what extent can each of the types of biases mentioned above manipulate the results obtained. To realize whether there is evidence that the described biases interfere in questionnaires’ results

10. Methods

11. Versions A and B

12. Data Analysis • The analysis of the answers given was only possible because we consider that the odds of obtaining a certain answer is similar in both groups of each class. • Our outcome was the rates in the answers given to supposedly biased and unbiased questions, comparing the rates to see if there was any significant differences. • To analyse our results we use the statistical analysis software SPSS 19.0.

13. Final Results and Discussion

14. Question A1 vs. B1-2 Ambiguousquestion • Unbiased question (B) : 1) Do you lend your tooth paste to other people? Yes [ ] No [ ] 2) Do you lend your tooth brush to other people? Yes [ ] No [ ] Biased question (A1) : Do you lend your tooth paste or tooth brush to other people? Yes [ ] No [ ]

15. Question A2 vs. B3 Biased Question (A2): When you take a bath, do you wash your genital area? Yes [ ] No [ ] Sensitivequestion Unbiased question (B3): • When you take a bath, do you wash your hair? • Yes [ ] • No [ ]

16. Question A3 vs. B4 Fakinggood Unbiased question (A3): How often do you have a shower in the week: • More than 6 days per week[ ] • 5-6 days per week [ ] • 2-4 days per week [ ] • 1 day per week[ ] • I never have a shower [ ] Biased question (B4): You have a shower everyday, don´t you? Yes [ ] No [ ]

17. Question A4 vs. B5 Uncommonword • Unbiased question (B5): • Do you consider that physical exercise is a relevant aspect of your health? • Yes [ ] • No [ ] Biased question (A4): Do you reckon that physical exercise is a germane aspect of your health? Yes [ ] No [ ]

18. Question A5 vs. B6 Belief vs. behaviour Biased question (B6): Do you think it is important to practice physical exercise at least 3 times a week? • Yes [ ] • No [ ] • Unbiased question (A5): • Do you practice physical exercise at least 3 times a week? • Yes [ ] • No [ ]

19. Question A6 vs. B7 Horizontal response format Biased question (B7): Your eating habits are: Excellent [ ] Very good [ ] Good [ ] Fair [ ] Somehow deficient [ ] Poor [ ] Very poor [ ] • Unbiased question (A6): • Your eating habits are: • Excellent [ ] • Very good [ ] • Good [ ] • Fair [ ] • Somehow deficient [ ] • Poor [ ] • Very poor [ ]

20. Question A7 vs. B8 “Neutral response” options • Unbiased question (B8): • Do you agree that McDonalds is responsible for the increase of hypertension rates? • Agree [ ] • Disagree [ ] Biased question (A7): Do you agree that McDonalds is responsible for the increase of hypertension rates? Agree [ ] Neutral opinion [ ] Disagree [ ]

21. Question A8 vs. B9 Faultyscale • Unbiased question (A8): • How many days per week do you dedicate to study anatomy? • 1 day [ ] • 2 days [ ] • 3 days [ ] • 4 days [ ] • 5 days [ ] • 6 days [ ] • 7 days [ ] Biased question (B9): How many days per week do you dedicate to study anatomy? 2 days [ ] 5 days [ ] 7days [ ]

22. Question A9 vs. B10 Leadingquestion Biased question (B10): Do you arrange activities with your friends, such as cinema, every week? • Yes [ ] • No [ ] • Unbiased question (A9): • Do you arrange activities with your friends every week? • Yes [ ] • No [ ]

23. Question A10 vs. B11 Technicaljargon • Unbiased question (B11): • Did you understand what you read in this questionnaire? • Yes [ ] • No [ ] Biased question (A10): Did you exercise your Wernicke’s area while responding to this questionnaire? Yes [ ] No [ ]

24. Conclusion Summing up, there are a lot of biases described in literature. Through this study, it has been concluded that some of them might work and others not. We cannot, however, extrapolate these results to the general population. http://us.cdn2.123rf.com/168nwm/texelart/texelart1011/texelart101100030/8220784-3d-human-by-the-symbol-of-victory-with-his-fingers.jpg

25. References (Presentation) M. Delgado-Rodríguez and J Llorca, Bias, J. Epidemiol. Community Health 2004;58;635-641 Bernard C.K. Choi and Anita W.P. Pak. A Catalog of Biases in Questionnaires. Preventing Chronic Diseases. 2005; 1; 13 http://www.statpac.com/surveys/undecided-category.htm

26. Afonso Quelhas André Santos Bárbara Araújo Carolina Silva Catarina Marques Cláudia Oliveira Laura Gonçalves Luís Sousa Marta Sanhá Rita Costa Tânia Costa