Biostatistics questions
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 Garter
 Posts: 3
 Joined: Sun May 07, 2006 6:27 pm
Biostatistics questions
I am not sure whether violoation of the assumptions of an analysis will or will not have influence on pvalue?
thanks
thanks
Violations of assumptions means that you are applying a test that you shouldn't be applying to your data. The pvalue may still be computed, but you cannot interpret it.
For example if your population has two maxima, and you are applying a ttest, which assumes a normal distribution, you may still get a pvalue, but whatever result it doesn"t mean anything. This mean that you should probably use another test, here a non parametric one.
For example if your population has two maxima, and you are applying a ttest, which assumes a normal distribution, you may still get a pvalue, but whatever result it doesn"t mean anything. This mean that you should probably use another test, here a non parametric one.
Patrick
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

 Garter
 Posts: 3
 Joined: Sun May 07, 2006 6:27 pm
No I am saying that even though you may always be able to compute a pvalue, if you violated the assumptions of your test in the beginning (if for example it assumes a normal distribution of your results and it is not true for your data) you should not draw any conclusion from your result.
The interpretation of the pvalue depends on the set of assumption in the beginning and can only be interpreted if you respect them. Find yourself a good biostatitics book if you want more explantions.
The interpretation of the pvalue depends on the set of assumption in the beginning and can only be interpreted if you respect them. Find yourself a good biostatitics book if you want more explantions.
Patrick
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
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