Ensuring Good Science Notes - Association, Correlation, and Causation PDF

ENSURING GOOD SCIENCE UNPACKING NOTIONS OF GOOD SCIENCE ASSOCIATION, CORRELATION AND CAUSATION ENSURING GOOD SCIENCE ASSOCIATION, CORRELATION AND CAUSATION Two variables (events or processes) can be related to each other in many ways Three important terms when describing such...

ENSURING GOOD SCIENCE UNPACKING NOTIONS OF GOOD SCIENCE ASSOCIATION, CORRELATION AND CAUSATION ENSURING GOOD SCIENCE ASSOCIATION, CORRELATION AND CAUSATION Two variables (events or processes) can be related to each other in many ways Three important terms when describing such relationships are: o Association o Correlation o Causation ENSURING GOOD SCIENCE ASSOCIATION Association implies a very general relationship: one variable provides information about another https://www.statology.org/correlation-vs-association/ ENSURING GOOD SCIENCE CORRELATION Correlation implies a more specific relationship: two variables are correlated when they display an increasing or decreasing trend https://www.statology.org/correlation-vs-association/ ENSURING GOOD SCIENCE ASSOCIATION VS. CORRELATION Biochar (charcoal-like product made from biomass waste) addition to soil is correlated with above ground biomass Gale et al. (2019) Science of The Total Environment ENSURING GOOD SCIENCE ASSOCIATION VS. CORRELATION Biochar addition is associated with above ground biomass BUT Biochar addition is NOT correlated with above ground biomass Gale et al. (2019) Science of The Total Environment ENSURING GOOD SCIENCE CAUSATION Causation (or Causality) implies that one event (or process) contributes to the production of another event (or process) ENSURING GOOD SCIENCE CAUSATION Causality comes in a variety of forms: ▪ Necessary cause: Represents a condition that must be A present for the effect to follow Unless A happens, B cannot happen However, sometimes the condition occurs without the outcome B ? A can occur without leading to B ENSURING GOOD SCIENCE CAUSATION Causality comes in a variety of forms: ▪ Necessary cause ▪ Sufficient cause: A ? Represents a condition that will guarantee the effect If A happens, B always happens However, the outcome may occur without the condition B B can occur in the absence of A ENSURING GOOD SCIENCE CAUSATION If one event causes another, it is possible that the first event is: Necessary but not sufficient https://hivinfo.nih.gov/understanding-hiv/infographics/hiv-and-aids-whats-difference ENSURING GOOD SCIENCE CAUSATION If one event causes another it is possible that the first event is: Necessary but not sufficient Sufficient but not necessary https://e-gmat.com/blogs/what-are-sufficient-but-not-necessary-conditions/ ENSURING GOOD SCIENCE CAUSATION If one event causes another it is possible that the first event is: Necessary but not sufficient Sufficient but not necessary Both necessary and sufficient https://www.netmeds.com/health-library/post/tay-sachs-disease- causes-symptoms-and-treatment-of-this-fatal-genetic-disorder ENSURING GOOD SCIENCE CAUSATION If one event causes another it is possible that the first event is: Necessary but not sufficient SARS-COV-2 and Fever Sufficient but not necessary Both necessary and sufficient Neither necessary nor sufficient Images: https://www.apsf.org/; https://health.clevelandclinic.org/ ENSURING GOOD SCIENCE UNPACKING NOTIONS OF GOOD SCIENCE ENSURING GOOD SCIENCE UNPACKING NOTIONS OF GOOD SCIENCE ENSURING GOOD SCIENCE UNPACKING NOTIONS OF GOOD SCIENCE CAUSATION ENSURING GOOD SCIENCE CAUSATION Usually it is never possible to prove causality, but only to show to what degree it is probable ENSURING GOOD SCIENCE CAUSATION Causality comes in a variety of forms: ▪ Necessary cause ▪ Sufficient cause ▪ Probabilistic cause: o Represents a condition that will increase the chance of the effect o A increases the chance of B occurring  ENSURING GOOD SCIENCE CAUSAL INFERENCE Deterministic causality Koch's postulates: 4 criteria designed to establish a causal relationship between a microbe and a disease (formulated in 1884). Koch applied the postulates to describe the etiology of cholera and tuberculosis, both of which are now ascribed to bacteria. https://commons.wikimedia.org/wiki/File:Koch%27s_Postulates.svg  ENSURING GOOD SCIENCE CAUSAL INFERENCE Deterministic causality Koch’s Postulates 1. The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms. 2. The microorganism must be isolated from a diseased organism and grown in pure culture. 3. The cultured microorganism should cause disease when introduced into a healthy organism. 4. The microorganism must be re-isolated from the inoculated, diseased experimental host and identi ed as being identical to the original speci c causative agent. https://commons.wikimedia.org/wiki/File:Koch%27s_Postulates.svg fi fi ENSURING GOOD SCIENCE CAUSAL INFERENCE Probabilistic causality In epidemiology, most causes have much weaker relationships to effects. For example, high cholesterol may lead to heart disease, but it need not (insufficient), and heart disease does not require a high cholesterol (unnecessary). The emphasis on multiple causes in probabilistic causality leads to expressions such as the web of causation, or chain of causation LDL = low-density lipoprotein https://www.wsj.com/articles/SB10001424052748704271804575405602444073276 ENSURING GOOD SCIENCE CORRELATION-VS-CAUSATION Correlation Does Not Imply Causation!! ENSURING GOOD SCIENCE CORRELATION-VS-CAUSATION