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Objectives

Objectives. To discuss threats to validity for the two articles To review for the midterm examination. Threats to Validity. Smoking prevention paper (Cameron, et al) Growth retardation paper (McDermott, et al). Figure 2 . Stroke mortality rates by birth cohort and age group in females.

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Objectives

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  1. Objectives • To discuss threats to validity for the two articles • To review for the midterm examination

  2. Threats to Validity • Smoking prevention paper (Cameron, et al) • Growth retardation paper (McDermott, et al)

  3. Figure 2. Stroke mortality rates by birth cohort and age group in females. From:   Medrano: Stroke, Volume 28(1).January 1997.40-44

  4. Discussion • Age effect: Mortality increased markedly with age in all cohorts for men and women alike, with rates being somewhat higher in men, especially in the younger generations. For any given age group, mortality was observed to vary with cohort, increasing in the older cohorts and decreasing in the more recent ones. The negative slope was less evident for men, the younger age groups, and the more recent cohorts. • A period effect: was also to be observed, since mortality peaked for all age groups in consecutive cohorts, meaning that the downward shift occurred in the same period for all birth cohorts and age groups. From age and year of birth, it can be deduced that this period must have been circa 1974 (1972-1976).

  5. Table 1. Age-specific rates (per 100000) for schizophrenia.From:   Takei: Psychol Med, Volume 26(5).September 1996.963-974

  6. Age--period--cohort Analysis of the Incidence of Schizophrenia in ScotlandTakei, Noriyoshi; Lewis, Glyn; Sham, Pak C.; Murray, Robin M. Psychological Medicine Volume 26(5)  September 1996  pp 963-974

  7. Discussion • Cohort effect is present • Age effect is present

  8. Rates • a.incidence density • b.cumulative incidence • c.point prevalence • d.period prevalence • e. odds for the disease of interest

  9. Study Design • a.case-cohort • b.case-control • c.case-control study within a defined cohort • d.nested case control • e.cohort • f.cross-sectional • g.ecologic • h.experimental

  10. Sun exposure and melanoma • A random-digit telephone survey of 580 person was conducted to examine the association of sun exposure and skin melanoma • Sun exposure was classified as low, medium and high using a standardized algorithm • Persons who had skin melanoma were compared to those who did not for sun exposure? • What type of study is this? • What other confounders should be considered?

  11. The association between sun exposure and skin melanoma What is the prevalence of skin melanoma? What is the prevalence of high sun exposure? What is the odds of having med/high exposure given that you Have skin melanoma compared to low exposure?

  12. Collapsing Categories

  13. ACL tear and gender What is the odds of being a women given you have An ACL tear compared to the odds of being a man?

  14. Crude and stratified Odds Ratios

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