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Thread: Nonparametric data analysis

  1. #16
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    Re: Nonparametric data analysis




    Quote Originally Posted by GretaGarbo

    But the null hypothesis in Mann Whitney is P(x1 > x0) = 0.5, where x0 is the [U
    age[/U] of those who are not sick and x1 is the age of those who are sick. But the age (or the relevant IV in this case) is not normal according to OP and possibly skewed and heteroscedastic, and Mann Whitney is sensitive to that (Search for Fagerland-Sandvik).
    In my research i have two different groups.one has the pathologic condition, another doesnot. Every of those groups can be described by 6(or more) parameters and these parameters in my case are amounts of iron deposition in differen brain regions. THe data of brain iron deposition is skewed, but the result of MW test showed the the brain iron deposition (in somebrain regions)differs statistically in those two groups, so i can use them for differentiating my two groups/

    THE QUESTION

    1/wHATS WRONG WHIS MY ANALISYS?
    2/ cAN I DO Something else besides this?
    Thanks alot/
    Last edited by Mykola; 11-16-2017 at 11:03 PM. Reason: bad english

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    Re: Nonparametric data analysis

    Quote Originally Posted by ondansetron View Post
    Here is a general comment, not particular to your post. Medical literature doesn't exactly use the right methods at the right time or in the right way (nor do they recognize statistics as something that does not follow a cookbook approach). So, the argument that medical publications use one method or do something one way is a poor argument. There is a lot of "oh, this group published with this analysis, that must be the right way to do it."
    tottally agree,and i`v seen those stuff many times (like the patients in the first group had 20+\-25 teeth) but as an examples i use only those articles where the main authors hi inedx is above 30, so i think they`re trying to use statistic in a correct way.
    Last edited by Mykola; 11-16-2017 at 11:16 PM. Reason: bed english

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    Re: Nonparametric data analysis

    Quote Originally Posted by Mykola View Post
    2/ cAN I DO Something else besides this?
    Yes, logistic regression, look at post #2.

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    Re: Nonparametric data analysis

    Quote Originally Posted by Mykola View Post
    tottally agree,and i`v seen those stuff many times (like the patients in the first group had 20+\-25 teeth) but as an examples i use only those articles where the main authors hi inedx is above 30, so i think they`re trying to use statistic in a correct way.
    If you are talking about an impact factor or something similar when you say "index" I can tell you that it doesn't matter as much. I've seen top journals with bad stats in articles by prominent universities and prominent researchers. It be very careful of equating publications with "good" statistical practice and interpretation.

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    Re: Nonparametric data analysis

    Quote Originally Posted by ondansetron View Post
    If you are talking about an impact factor or something similar when you say "index" I can tell you that it doesn't matter as much. I've seen top journals with bad stats in articles by prominent universities and prominent researchers. It be very careful of equating publications with "good" statistical practice and interpretation.
    i can show u the data, will anybody try to help?

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    Re: Nonparametric data analysis

    Quote Originally Posted by GretaGarbo View Post
    Yes, logistic regression, look at post #2.
    And its ok thst. The data is skewed?

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    Re: Nonparametric data analysis


    Quote Originally Posted by Mykola View Post
    And its ok thst.
    Don't understand.

    Quote Originally Posted by Mykola View Post
    The data is skewed?
    That's OK. It is based on the binomial distribution as you said in your first post. Not on the normal dist.

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