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Flashcards

Cross sectional

maxytrejo1 Epid college Inglês 67 flashcards

Flashcards do conjunto (67)

  1. 1In an experimental epi study, the investigator___randomyl assigns treament (esposure ) to study participants, it has adv and disadv
  2. 2In an observational study, the investigator can only___observe outsomes associates with the individual esposures experinced by the study participants.
  3. 3In contrast to a RCT, observational studies are notassighned
  4. 4Most epid. studies areobservational
  5. 5Epid studies are divided intoexperimental and observational
  6. 6Observational studies are divided intoecological, cross sectional, case control and cohort
  7. 7Study designs can be __hybrids and are not necessarily mutually exclusive
  8. 8Ecological aretime- trend (past) OR Present period/ aggregate data (present), Historical data (yes/no)
  9. 9In a cross sectional:Exposure and disease (present), no historical data
  10. 10In a case controlDisease (presnt) and looks back to exposure (past), no hisorical data
  11. 11In a Retrospective cohortdisease is in the present and looks back to exposure (past), There is historical data
  12. 12Propective cohortExposure in the present and disease in the future, no hissotical data
  13. 13which has historicla dataecological (yes/no) and Retorspective cohort
  14. 14Who has in the pastEcological, case control and retorspective
  15. 15Who has in the futreprospective cohort
  16. 16Ecological studies are associated between anexposure and in outcome
  17. 17In ecological studies the unity of analysis ispopulation or groups of people rather than individual
  18. 18In ecological, each group is clasified with respect toexposure aans disease status
  19. 19In ecological studies:what is missing on the joint distribution variables within each group (2x2 table)individual level data is missing
  20. 20Ecological studies usually describe groups defined bygeography and/or time
  21. 21Aggregate measures aresummers of observations derived from individuals in each groups: % of pop over 65
  22. 22Environmental measure:physical characteristics of the place in which members of each group live or work: concentration of airborne mercury in Santa Cruz
  23. 23Global Measures areattributes of groups for which there is no distinct analog at the individual level:gun control
  24. 24What is soem rationale for ecological studies1. Low cost and convenience 2. Measurement limitations of individual studies 3. Design limitation of level studies 4. Useful for generating hypothesis
  25. 25Ecological studies: Low cost and convenienceStudies often involve data from population registries, vital records and other secondary sources (dont need to collect data)
  26. 26Ecological studies: Measurment Limitations of individual-level studiesoften difficult to assess environmental exposure for individuals
  27. 27Ecological Studies: Design limitations of individual level studiesminimal variability in exposure within a given study are: intra group variabilty is small, but inter group variabilty is large
  28. 28Study desighns for ecological studies1.
    Multi group 2. Time Trend 3. Mixed Study
  29. 29Eco: Multiple Group:same time,differnt group/region; Exploratory: Compares disease rates of different groups (migration studies)
  30. 30Multi Group can also beAnalytic: Compare exposure and disease by country, dietary fat intake and breast cancer
  31. 31Multi Group has 2 typesexploratory and Analytic
  32. 32Eco: Time trenddiffernt time, same group / region
  33. 33Eco: Time TrendExploratory: age-period-cohort analysis
  34. 34Eco:Time trendAnalytic: Compare changes in exposure and disease over time in the UK, tobacoo consumption and lung cancer from 1900-1950
  35. 352 types of time trend eco studiesExploratory and Analytic
  36. 36Eco : Mixed studiesincorporate both desighs
  37. 37The dietary fat intake and breast cancer by country ( incidence rate per year vs per capital supply of fat calories ) are examples ofmultiple group (analytic) ecological study
  38. 38Tobacco use and lung cancer in the UK ( death rate cancer of the lung per million and consumption of tabacco and cigarette lbs per person vs yearexample of time trend (analytic) ecological study
  39. 39Male circumcision are examples ofvariations in magnatude of HIV epidemic in Africa are striking
  40. 40The purpose pg the male hiv circum and HIV was toexplor the realtionship between HIV and seroprevance and proportion of uncircumcised males in african countries
  41. 41Why should you conduct the ecological study of male circum and HIVto explose a potential hypothesis using exsisting data
  42. 42The study design for the male circum and hivexample of a multi group
    (analytic)eco study, examined prevalence of male circumcision an d hiv in 140 locations/41 countires
  43. 43What are some study limitation of the eco studythe population level correlation between male circumcision and hiv prevalence does not prove a cause and effect relationship
  44. 44What are potential confounders of the associationplaces of introduction of HIV (uncir//cirm), Differences in sexual behavior(#of sexual partners, use of protection), Differnce in religion and practices (christians vs. muslims), methodologic problems
  45. 45in Ecological studies there aremethodologic problems
  46. 46method. propblem: Ecological falacy (bias) occurs whenan aggregate level association is inferred as an individual level association
  47. 47Ecological bias can arise fromConfounding by group
  48. 48Confounding by group isunique to ecological studies:1. extraneous risk factors are differently distributed across groups 2. exposure effect on disease risk differs at the individual and aggregate levels
  49. 49Confounding by Group examplesusicde rates in Catholic vs Prtoestant
  50. 50The fit of the ecological regression model provides no indication ofpresence , direction, or magnitude of bias
  51. 51excelent model fit does notpreclude ecological bias
  52. 52what bias could exist in the ecological study of suicidemeans of resolving ecological bias
  53. 53If possible in an ecolog we must utilizesmaller unity to make groups more homogeneous with respect to expose
  54. 54Associations may ___ be cusual in eco studiesNOT
  55. 55Association may not be causal becuase1. could be due to a third factor or intermediate variable 2. limited for testing etiologicl hypothesis 3. Temporal ambiguity
  56. 56Temporal ambiguity is true forcross sectional and ecolgical studies
  57. 57Issues with eco stidiesCollinearity and association may not be causal
  58. 58Collinearity in eco stuidiescertain predictors such as sociodemographics and environmental factors , tend to be highly corelated
  59. 59Colinearity is more inecological studies and individual level studies
  60. 60Cross sectional examineslooks at preset and examines disease between exposure and disease at a single point in time
  61. 61In corss sectional: individual isunit of analysis
  62. 62Study population is selcted froma single target populatio withought regard to 1. exposure OR 2. disease status
  63. 63Cross section is asnapshot in time aka a prevalence study
  64. 64Advantages of Cross sectional1. quick and inexpensive 2. useful foe describing characteristics of the target population 3. Findings may be more representative of general population than other epi studies 4. Association are useful for hypothesis generation
  65. 65Cross sec: Quick and inexpensive:useful for health planning and best suited for disease of slow onset and long duration
  66. 66Cross sectiona studies: Usefull for describing chracteristics of the target pop:can provide estimates of disease and exposure
  67. 67Cross sectiona Disadvantages:1. cannot establish a temporal relationship 2. inefficient when exposure or outcome are are 3. may be useful for etologic (causal) research (can only estimate prevalence not incidence the risk of death

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college Epid (Final) FlashCards sobre Cross sectional, criado por maxytrejo1 em 13-05-2014.
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maxytrejo1
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