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Indeed they are, but according to the null hypothesis precept, without persuasive contradicting evidence, there is no association. The burden is on experimental

by lutusp 12y ago

Indeed they are, but according to the null hypothesis precept, without persuasive contradicting evidence, there is no association. The burden is on experimental evidence to contradict that assumption, and if positive evidence isn't present, then the default assumption is correct. Think about what proving no association actually means. That would require proof of a negative, which is a widely recognized logical error, an impossible burden. To see why, imagine that I believe in Bigfoot and I will continue to believe until someone proves he doesn't exist. But no one can prove Bigfoot isn't hiding under some rock on a faraway planet, therefore I am justified in my belief. My belief is supported by an impossible evidentiary burden. This is why scientists rely on the null hypothesis -- contradicting it requires positive evidence. Its opposite requires negative evidence.

zmmmmm 12y ago
> if positive evidence isn't present, then the default assumption is correct What you have said above is horribly wrong and is exactly the point I am making. If it is true then I can prove anything I like just by designing a bad enough experiment. For example, suppose I want to prove that the moon is made of green cheese. I can start with a null hypothesis that it IS made of green cheese. Then I can point my telescope in the wrong direction and find no evidence that it is not made of green cheese. Using your logic I am free to then conclude that my null hypothesis is true. You cannot just make any null hypothesis you want and then when you fail to prove it untrue, claim it is true. If you want to make a positive claim about the null hypothesis (for example, claim there is no association between salt and blood pressure) then you have to test it directly with positive evidence in its own right.
- lutusp 12y ago
  >> if positive evidence isn't present, then the default assumption is correct > What you have said above is horribly wrong and is exactly the point I am making. If it is true then I can prove anything I like just by designing a bad enough experiment. You obviously do not understand the null hypothesis. Under the null hypothesis, a claim is assumed to be false unless and until persuasive evidence shows otherwise. Only psychologists think a bad experiment contradicts the default assumption of no effect. Serious science must pass muster with other equally serious scientists, who will call out anyone trying to cheat. > For example, suppose I want to prove that the moon is made of green cheese. I can start with a null hypothesis that it IS made of green cheese. That is certainly not what "null hypothesis" means -- your utterly mistaken view asserts its opposite, the alternative hypothesis. Please learn anything at all about this topic before assuming you understand it. > You cannot just make any null hypothesis you want and then when you fail to prove it untrue, claim it is true. Honestly. Learn what it means before trying to discuss it. http://en.wikipedia.org/wiki/Null_hypothesis http://en.wikipedia.org/wiki/Null_hypothesis Quote: "In statistical inference of observed data of a scientific experiment, the null hypothesis refers to a general statement or default position that there is no relationship between two measured phenomena. Rejecting or disproving the null hypothesis – and thus concluding that there are grounds for believing that there is a relationship between two phenomena or that a potential treatment has a measurable effect – is a central task in the modern practice of science, and gives a precise sense in which a claim is capable of being proven false."
  - zmmmmm 12y ago
    Well, your insulting tone is not particularly conducive to ongoing discussion ... but can't you see that Wikipedia is exactly contradicting you? Try and find anything there that backs up this statement: >> if positive evidence isn't present, then the default assumption is correct Quoting from the same page: "...it should be noted that the null hypothesis is never proved or established, but is possibly disproved, in the course of experimentation." And again: "We may, however, choose any null hypothesis we please, provided it is exact."
    - lutusp 12y ago
      > can't you see that Wikipedia is exactly contradicting you? You need to learn about the null hypothesis. And science. The null hypothesis denies the reality of the asserted hypothesis until positive evidence supports it. How difficult is that? The default assumption is that there is no effect, no connection between a stated hypothesis and reality. If I make the claim that Bigfoot exists, and then set out to test my claim using science, under the null hypothesis the default assumption is that Bigfoot does not exist. This means you have it exactly backwards. > ... your insulting tone is not particularly conducive to ongoing discussion A description is not an insult. Learn this difference also. Learn about the null hypothesis. Discover that the null hypothesis cannot be used to make a positive claim or assertion, as you did earlier with your green cheese example. That is reserved to the alternative hypothesis, which is how pseudoscience works, i.e. make a claim and wait for someone else to disprove it with the impossible standard of "proof of a negative" or "absence of evidence": http://en.wikipedia.org/wiki/Evidence_of_absence http://en.wikipedia.org/wiki/Evidence_of_absence

by lutusp 12y ago

zmmmmm 12y ago

> if positive evidence isn't present, then the default assumption is correct What you have said above is horribly wrong and is exactly the point I am making. If it is true then I can prove anything I like just by designing a bad enough experiment. For example, suppose I want to prove that the moon is made of green cheese. I can start with a null hypothesis that it IS made of green cheese. Then I can point my telescope in the wrong direction and find no evidence that it is not made of green cheese. Using your logic I am free to then conclude that my null hypothesis is true. You cannot just make any null hypothesis you want and then when you fail to prove it untrue, claim it is true. If you want to make a positive claim about the null hypothesis (for example, claim there is no association between salt and blood pressure) then you have to test it directly with positive evidence in its own right.

lutusp 12y ago
>> if positive evidence isn't present, then the default assumption is correct > What you have said above is horribly wrong and is exactly the point I am making. If it is true then I can prove anything I like just by designing a bad enough experiment. You obviously do not understand the null hypothesis. Under the null hypothesis, a claim is assumed to be false unless and until persuasive evidence shows otherwise. Only psychologists think a bad experiment contradicts the default assumption of no effect. Serious science must pass muster with other equally serious scientists, who will call out anyone trying to cheat. > For example, suppose I want to prove that the moon is made of green cheese. I can start with a null hypothesis that it IS made of green cheese. That is certainly not what "null hypothesis" means -- your utterly mistaken view asserts its opposite, the alternative hypothesis. Please learn anything at all about this topic before assuming you understand it. > You cannot just make any null hypothesis you want and then when you fail to prove it untrue, claim it is true. Honestly. Learn what it means before trying to discuss it. http://en.wikipedia.org/wiki/Null_hypothesis http://en.wikipedia.org/wiki/Null_hypothesis Quote: "In statistical inference of observed data of a scientific experiment, the null hypothesis refers to a general statement or default position that there is no relationship between two measured phenomena. Rejecting or disproving the null hypothesis – and thus concluding that there are grounds for believing that there is a relationship between two phenomena or that a potential treatment has a measurable effect – is a central task in the modern practice of science, and gives a precise sense in which a claim is capable of being proven false."
- zmmmmm 12y ago
  Well, your insulting tone is not particularly conducive to ongoing discussion ... but can't you see that Wikipedia is exactly contradicting you? Try and find anything there that backs up this statement: >> if positive evidence isn't present, then the default assumption is correct Quoting from the same page: "...it should be noted that the null hypothesis is never proved or established, but is possibly disproved, in the course of experimentation." And again: "We may, however, choose any null hypothesis we please, provided it is exact."
  - lutusp 12y ago
    > can't you see that Wikipedia is exactly contradicting you? You need to learn about the null hypothesis. And science. The null hypothesis denies the reality of the asserted hypothesis until positive evidence supports it. How difficult is that? The default assumption is that there is no effect, no connection between a stated hypothesis and reality. If I make the claim that Bigfoot exists, and then set out to test my claim using science, under the null hypothesis the default assumption is that Bigfoot does not exist. This means you have it exactly backwards. > ... your insulting tone is not particularly conducive to ongoing discussion A description is not an insult. Learn this difference also. Learn about the null hypothesis. Discover that the null hypothesis cannot be used to make a positive claim or assertion, as you did earlier with your green cheese example. That is reserved to the alternative hypothesis, which is how pseudoscience works, i.e. make a claim and wait for someone else to disprove it with the impossible standard of "proof of a negative" or "absence of evidence": http://en.wikipedia.org/wiki/Evidence_of_absence http://en.wikipedia.org/wiki/Evidence_of_absence