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Considering 3 rd Factor (S) in Causality

Considering 3 rd Factor (S) in Causality. 3 rd variable(s). Exposure 1 st var. Outcome 2 nd var. Kinds of RELATIONSHIPS OF 3 rd VARIABLE(S) IN RESEARCH. CONFOUNDING MEDIATION COLLINEARITY EFFECT MODIFICATION (INTERACTION OR MODERATION). A confusion of effect. Some points in:.

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Considering 3 rd Factor (S) in Causality

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  1. Considering 3rd Factor(S) in Causality 3rd variable(s) Exposure 1stvar Outcome 2ndvar D. Khalili

  2. Kinds of RELATIONSHIPS OF3rd VARIABLE(S) IN RESEARCH • CONFOUNDING • MEDIATION • COLLINEARITY • EFFECT MODIFICATION (INTERACTION OR MODERATION) D. Khalili

  3. A confusion of effect D. Khalili

  4. Some points in: D. Khalili

  5. Some points in: Effect Modification • It’s not a bias. • Global analysis / Crude OR ismeaningless. • Results should beanalysed in each stratum separately. D. Khalili

  6. a a1 a2 b b1 b2 OR1 c c2 c1 d d2 d1 ≠ levels ofthird factor OR2 Strategy to take into accounta third factor in data analysis 1) Crude analysis • 2) Stratified analysis Crude OR D. Khalili

  7. Strategy to take into accounta third factor in data analysis • 3) Compare stratifiedORs: 4) Where is the crude OR? D. Khalili

  8. OR1 Crude OR OR2 Strategy to take into accounta third factor in data analysis • 5a) • OR1 ≠ OR2 Third factor = Effect modifier If it is clinically important Don’tcompute an adjusted OR Report Stratum-specificresults of the association betweenexposure and outcome D. Khalili

  9. OR1 OR2 Crude OR Strategy to take into accounta third factor in data analysis 5b) OR1  OR2 Computation of adjusted OR

  10. OR1 Crude OR OR2 Strategy to take into accounta third factor in data analysis • 5c) • OR1  OR2 ORadORCrude Third factor = no role Use crude OR to measure the association between exposure and outcome D. Khalili

  11. a2 a1 a2 a2 a1 ai a2 ai ai ai ai a1 a3 a1 a1 a1 a2 a1 a2 ai a1 ai a2 a a2 ai a2 a1 a2 a1 ai ai a2 a1 ai a1 a1 ai a1 a2 a1 ai a2 a2 ai ai ai a2 a1 ai a1 a2 a2 bi b1 b1 b2 bi b1 b1 b2 b2 bi b2 b1 bi b3 bi b2 b1 b2 b bi b1 b2 bi b2 bi b2 b2 bi bi b2 b1 bi b2 b2 b2 b1 bi b2 b2 b1 bi bi b1 bi b1 bi b1 b2 bi b1 b1 b1 b1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 OR1 c1 c2 ci c2 ci c2 c2 c1 c1 c2 ci c2 c1 c1 ci c1 ci c1 c1 c1 ci c2 ci ci c1 ci c3 ci c2 ci c2 c1 c2 c c2 c1 c1 c1 ci ci c2 ci ci ci c1 c2 c1 c2 c2 c2 c1 ci c2 d1 d2 di d1 d1 d2 di d2 d2 di d1 d2 d2 d1 d di d1 di di d2 d2 d1 di di di d1 d1 d2 d2 d1 d2 di d1 d2 d1 d1 d2 d2 d3 di di di d1 d2 d1 d2 di d1 d1 di di d2 di OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR2 OR3 etc. OR crude ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi ORi How to take into accountseveral potential third factors D. Khalili

  12. How to take into accountseveral potential third factors Multivariable analysis … The most practical one: Logistic Regression D. Khalili

  13. Should we consider any interaction? D. Khalili

  14. Research by Love . . . از توجه شما سپاسگزارم D. Khalili

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