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short slides on correlation / causation

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  1. 1. the dangers of correlation and causation a casual warning ice cream can turn you into a murderer?
  2. 2. Correlations show when there is a pattern or link in way two variables change Different kinds of linear correlations R2 measures the strength of a correlation 0 none 1 perfect
  3. 3. Consider the strength of this claim
  4. 4. Designing Studies The minimal conditions establishing cause and effect in medical diagnosis. The Bradford Hill Criteria Temporality Sir Austin Bradford Hill (1897 – 1991) effect in that the effect occurs after the cause. Also, if it is to be expected that there is some delay between cause an Strength and association tion between these in repeated events or experiments. Full strength correlation has a coefficient of 1. A weaker assoc Biological gradient (dose-response) relationship between the dose given and the reaction of the patient. This may not be a simple linear relationship and Consistency ot prove a general cause and effect in wider contexts. To prove a treatment is useful, it must give consistent results in Plausibility ries and results. If a causal relationship appears to be outside of current science then significant additional hypothesi Specificity ere is no other plausible explanation. This is not always the case in medicine where any given symptoms may have a Evidence xperiments, where many significant variables are held stable to prevent them interfering with the results. Other eviden
  5. 5. Sir Austin Bradford Hill Analogy hen other factors similar or analogous to the supposed cause should also be considered and identified as a possible Coherence xperiments in which variables are controlled and external everyday evidence are in alignment, then it is said that there
  6. 6. Evaluate the following … -ice cream and sun-burn are correlated positively -lead-poisoning and risk of being hit by a car are collelated positively -There is a negative correlation between the use of sun-cream and the risk of having an accident in a swimming pool -ice cream eating is positively correlated with the incidence of murder