POPM 3240 Lecture Notes - Lecture 2: Recall Bias, Observational Error, Pancreatic Cancer
11 Sep 2017
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Document Summary
There are three main types of bias that we will discuss in this unit: selection. A causal pathway can be either direct or indirect: direct causation indicates that a factor directly causes a disease or health outcome, without any steps in between. Indirect causation indicates that a factor causes disease, but not before going through at least one intermediate step. When discussing types of causal relationships, gordis (2014) lays out four types of relationships, where a factor is: necessary and sufficient, necessary, but not sufficient, sufficient, but not necessary; or, neither necessary, nor sufficient. In this figure, we have listed three component causes (a, b, c). When these factors are present in combination they equate to a sufficient cause, which ultimately causes the outcome (i. e. , disease). Three things are required in order to contract hiv: transmission activity: sharing needle, mother- to-child, unprotected sex, receiving blood, transmission fluid: blood, semen, breast milk, vaginal fluid, rectal fluid.
