University:
The University Of Western Ontario
Course:
Biology 2290F | Scientific Method in Biology
Academic year:

2022
Views:

304

Pages:

2
Author:

Kyuwon J.

Necessary and Sufficient Causes ● Necessary Cause ○ Presence is required for occurrence of the effect ■ If A is necessary for B then B cannot occur without A being present ● Sufficient Cause ○ Condition,factor or event that is able to produce a given outcome ■ If A is sufficient for B then if A present B will occur Sufficient and Component Causes ● Necessary Cause ○ Each factor is component causes ○ Necessary in the sense that without any one of which the disease would not have occured ● Key Implication of Model ○ Multicausality ■ Every causal mechanism involves the joint action of multiple component causes ■ Usually mixture of genetic and environmental componentes causes for every casual mechanisms ● ex) hip fracture ○ Genetics: influence with, gait, behavior, recovery from previous trauma ○ Previous brain injury leading to parament equilibrium disturbance ■ Fall years later ○ Types of shoe person wears ○ Construction of path ■ Handrail,wind, ice Sufficient and component Causes ● Is each factor necessary? ● Is each factor sufficient ● For each individual cae ○ All component causes are necessary for that individual ○ None are sufficient Necessary and Sufficient Causes for population ● Causes can be ○ Necessary and sufficient ■ Trisomy 22 and Down Syndrome ○ Unnecessary but sufficient ■ Hysterectomy and Pregnancy ○ Necessary but insufficient ■ Alcohol consumption and Alcoholism ○ Unnecessary and insufficient ■ Smoking and lung cancer Counterfactual/Potential Outcomes Potential Outcomes for Binary Outcome/Exposure