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Weighing the Evidence

This investigation explores the causality of an association and its impact on disease prevention. It examines disease distribution, association, causal relationship, prevention strategies, and the effectiveness of interventions.

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Weighing the Evidence

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  1. RR = 7 Weighing the Evidence Is the association causal? Weighing the Evidence Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  2. Hypotheses 1 How is this disease distributed? 2 Is there an association? Why did the exposure and the disease turn up together? 3 Is the association causal? 4 What should be done to prevent the disease? 5 Did the prevention strategy work? Where are we and where are we going? What’s my hypothesis? Did the exposure and the disease turn up together? Intro to Epidemiology – Investigation 3-7: Weighing the Evidence

  3. Review 1. Cause 2. Chance 3. Confounding Reversed Time Order 4. 5. Selection Bias Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  4. Review Epi Speak Epidemiology The study of how and why diseases or other health-related conditions are distributed in a population the way they are, in other words, why some people get sick and others do not. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  5. causal, …. X … and the hypothesized causal exposure were avoided or eliminated, what would happen to the outcome? Explanations for Finding an Association If an association were causal, …. ? Hypothesized Exposure Outcome X Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  6. X … and the hypothesized causal exposure were avoided or eliminated, what would happen to the outcome? Explanations for Finding an Association If an association were found due to chance, …. ? Hypothesized Exposure Outcome Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  7. found due to confounding, …. Unobserved Exposure X … and the hypothesized causal exposure were avoided or eliminated, what would happen to the outcome? Explanations for Finding an Association If the association were ? Hypothesized Exposure Outcome Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  8. found due to reversed time-order, …. X … and the hypothesized causal exposure were avoided or eliminated, what would happen to the outcome? Explanations for Finding an Association If an association were ? Hypothesized Exposure Outcome Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  9. X … and the hypothesized causal exposure were avoided or eliminated, what would happen to the outcome? Explanations for Finding an Association If an association were found due to selection bias, …. ? Hypothesized Exposure Outcome Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  10. Explanations for Finding an Association Why would an exposure and an outcometurn up together? • Cause • Chance • Confounding • Reversed Time Order • Selection Bias • Cause Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  11. The Weight of the Evidence Guilty or Not guilty? Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  12. The Weight of the Evidence Causal or Not Causal? Guilt or Innocence? Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  13. The Weight of the Evidence Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  14. The Weight of the Evidence Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  15. The Weight of the Evidence “Does Playing Video Games Cause Asthma?” Explain why you believe that playing video games does or does not cause asthma Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  16. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  17. 1 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 1. “… they found that children who visited the ER because of an asthma attack werefour times as likelyto play video games as the control group of hospitalized children who visited the ER because of broken bones.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  18. 1 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 1. “… they found that children who visited the ER because of an asthma attack werefour times as likelyto play video games as the control group of hospitalized children who visited the ER because of broken bones.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  19. 1 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 1. “… they found that children who visited the ER because of an asthma attack werefour times as likelyto play video games as the control group of hospitalized children who visited the ER because of broken bones.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  20. 2 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 2. “As the frequency of ER visits increased, the amount of time spent playing video games increased up to a point.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  21. 2 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 2. “As the frequency of ER visits increased, the amount of time spent playing video games increased up to a point.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  22. 2 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 2. “As the frequency of ER visits increased, the amount of time spent playing video games increased up to a point.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  23. 3 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 4 3. “… they had found an association between playing video games and asthma, an association that hadbeen found only once before.” 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  24. 3 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 4 3. “… they had found an association between playing video games and asthma, an association that hadbeen found only once before.” 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  25. 3 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 4 3. “… they had found an association between playing video games and asthma, an association that hadbeen found only once before.” 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  26. 4 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 4. “… the research designdid not determine the time-order to the playing of the video games and the asthma.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  27. 4 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 4. “… the research designdid not determine the time-order to the playing of the video games and the asthma.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  28. 4 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 4. “… the research designdid not determine the time-order to the playing of the video games and the asthma.” 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  29. 5 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 5. “… there have beenseveral hintsof an association between playing video games and asthma before.“ 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  30. 5 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 5. “… there have beenseveral hintsof an association between playing video games and asthma before.“ 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  31. 5 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 5. “… there have beenseveral hintsof an association between playing video games and asthma before.“ 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  32. 6 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 6. “Itis a mystery why, biologically, playing video games would increase the risk of asthma.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  33. 6 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 6.“Itis a mystery why, biologically, playing video games would increase the risk of asthma.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  34. 6 Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 6. “Itis a mystery why, biologically, playing video games would increase the risk of asthma.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  35. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 2 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  36. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1   What is the strength of the association between the exposure and the disease? 2 3 4 1. “… they found that children who visited the ER because of an asthma attack played video games were four times as likely to play video games as the control group of hospitalized children who visited the ER because of broken bones.” 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  37. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1   Have studies established that the risk factor comes before the disease? 2 3 4 5 4. “… the research design did not determine the time-order of the playing of the video games and the asthma.” 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  38. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1   Is the finding consistent? Has it been replicated by others in other places? 2 3 4 3. “… they had found an association between playing video games and asthma, an association that had been found only once before.” 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  39. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 Do the implications of the observed findings make biological sense? 2 3 6. “It is a mystery, biologically, why playing video games would increase the risk of asthma. “ 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  40. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1   Can a dose-response be demonstrated? 2 3 2. “As the frequency of ER visits increased, a correlation with an increased amount of time spent playing video games was observed up to a point.” 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  41. Is the association causal? More Persuasive Less Persuasive I would be more likely to believe an exposure caused an outcome if …. 1 Is the new finding coherent with earlier knowledge about the risk factor and the disease? 5. “… there have been several hints of an association between playing video games and asthma before.“ 2 3 4 5 6 Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  42. Hypotheses 1 How is this disease distributed? 2 Is there an association? Have studies established that the risk factor comes before the disease? Is the finding coherent with earlier knowledge of the risk factor and the disease? Do the implications of the findings make biological sense? What is the strength of the association between the risk factor and the disease? Can a dose-response be demonstrated? Is the finding consistent? Has it been replicated by others in other places? 1. 4. 3 Is the association causal? 5. 2. 3. 4 What should be done to prevent the disease? 6. 5 Did the prevention strategy work? Questions for Evaluating Evidence for a Causal Association Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  43. Epi Speak Epi Speak Strength of Association A criterion for judging causality. The size of the relative risk. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  44. Epi Speak Epi Speak Dose-Response Relationship A criterion for judging causality. The degree to which risk increases as exposure increases. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  45. Epi Speak Epi Speak Consistency A criterion for judging causality. Finding similar results in studies done in different investigations, using different populations, and using different methods. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  46. Epi Speak Epi Speak Time Order A criterion for judging causality. The degree to which evidence can show that the hypothesized cause actually came before the outcome. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  47. Epi Speak Epi Speak Coherence A criterion for judging causality.  The extent to which a hypothesized causal association is compatible with pre-existing theory and knowledge. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  48. Epi Speak Epi Speak Biological Sense A criterion for judging causality. The extent to which a hypothesized causal association is coherent with previously existing biological or medical knowledge. Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  49. Is the association causal? Association Found Between Coffee and Diabetes Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

  50. 7 Association Found Between Coffee and Diabetes Intro to Epidemiology - Investigation 3-7: Weighing the Evidence

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