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causation and correlation whats the difference


HutchDan

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Help me with this example:

Is there a causation between cancer and smoking or just a strong correlation? is it a causation if smoking will always cause a physical change in your cells, which in turn causes cancer, or is it a causation between smoking and causing a change in your cells but not between smoking and getting cancer, because there are many other factors (immunity, genes, etc.) that determine whether you are going to develop cancer at all.

hope you get what im saying, cheers :)

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the difference is that correlation, for instance in scatter plot graph, shows that there is a relationship b/w the variable, in this case smoking and cancer. Smoking seems to cause cancer but causation is not determined until experiments had been conducted to conclude so, thus it's causation.

Hope that makes sense.

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Correlational: data about 2 variables are gathered and compared against each other to see if there is a relationship. this does not mean one factor causes the effect in the other factor, it is merely correlational (i.e. could be coincidence)

Causational: experiments are carried out by controlling variables, then seeing the effect of changing the independent variable on the dependent variable. this provides information that one factor causes a change in the other, because all other factors have been controlled.

About your argument, I think smoking does cause cancer but it may do this on its own or with other factors which also cause cancer. there are also cancers which are not caused by smoking. This argument is a bit difficult, because scientific research does say smoking causes cancer, but you cannot specifically carry out an experiment to control variables and see if smoking causes cancer or not because 1) it is highly unethical and 2) it is physically impossible to control other factors that can cause smoking

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The problem with smoking and cancer is that you're never going to have a clear cause-effect pattern because of other variables. Immunity and genes actually I don't think play much of a role in terms of susceptibility. There's no real genetic lung cancer syndrome and you can knock somebody's immune system up and down with very little risk of them developing lung cancer beyond the risk they would have had anyway - although some other cancers are immunologically related, lung not so much.

More like random chance, how functional your DNA repair mechanisms are feeling, intact mechanisms of apoptosis and of course exposure to other factors which could induce mutations in cellular DNA. Mostly it's random chance. And of course if you mount a constant assault on your DNA via smoking then your event rate goes up dramatically and accordingly the incidence of mutation goes up. The more mutations the more statistically likely that one will be significant, and the more significant mutations the higher the risk of other significant mutations until you've accumulated enough key mutations to de-regulate the cycle so your mutations breed further mutations in an un-restrained manner... and so on. Risk rises.

Correlation does go down quite far though. If you're interested in some more concrete evidence, then there's an interesting study where they've looked at lung cancer in smokers vs non-smokers and found specific patterns of mutation in p53 (a very important tumour suppressor gene - once you've knocked out p53 the cell cycle loses its regulation and cells can proliferate like crazy without spontaneously dying when they realise they're messing up because their protection against this is severely undermined), thought to be related to the specific type of damage done by the chemicals found in smoke. On the level of a chemical reaction you actually can consider cause and effect because the only variables are just that - two chemicals.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1533115/

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The problem with smoking and cancer is that you're never going to have a clear cause-effect pattern because of other variables. Immunity and genes actually I don't think play much of a role in terms of susceptibility. There's no real genetic lung cancer syndrome and you can knock somebody's immune system up and down with very little risk of them developing lung cancer beyond the risk they would have had anyway - although some other cancers are immunologically related, lung not so much.

More like random chance, how functional your DNA repair mechanisms are feeling, intact mechanisms of apoptosis and of course exposure to other factors which could induce mutations in cellular DNA. Mostly it's random chance. And of course if you mount a constant assault on your DNA via smoking then your event rate goes up dramatically and accordingly the incidence of mutation goes up. The more mutations the more statistically likely that one will be significant, and the more significant mutations the higher the risk of other significant mutations until you've accumulated enough key mutations to de-regulate the cycle so your mutations breed further mutations in an un-restrained manner... and so on. Risk rises.

Correlation does go down quite far though. If you're interested in some more concrete evidence, then there's an interesting study where they've looked at lung cancer in smokers vs non-smokers and found specific patterns of mutation in p53 (a very important tumour suppressor gene - once you've knocked out p53 the cell cycle loses its regulation and cells can proliferate like crazy without spontaneously dying when they realise they're messing up because their protection against this is severely undermined), thought to be related to the specific type of damage done by the chemicals found in smoke. On the level of a chemical reaction you actually can consider cause and effect because the only variables are just that - two chemicals.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1533115/

very good answer

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