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The Microbiome in Posttraumatic Stress Disorder and Trauma-Exposed Controls: An Exploratory Study

Discussion in 'Health News and Research unrelated to ME/CFS' started by Andy, Oct 28, 2017.

  1. Andy

    Andy Committee Member

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    Paywalled at http://journals.lww.com/psychosomat...iome_in_Posttraumatic_Stress_Disorder.14.aspx

    Article on paper - https://www.sciencedaily.com/releases/2017/10/171025103140.htm
     
  2. Trish

    Trish Moderator Staff Member

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    As we know, correlation does not imply causation. Does trauma cause stress that leads to upset in gut flora, or does imbalance in gut flora predispose to suffering PTSD following trauma? Or is some other factor influencing both.

    Or is it such weak evidence that it could be chance variation. p = 0.035, PTSD sample size 18, 12 control. Several different associations tested, only one was significant at 5%level.

    We are none the wiser.
     
  3. JCB

    JCB Senior Member (Voting Rights)

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    random forest analysis? WTF? Is this some form of p-hacking or is there something more to it?
     
  4. Woolie

    Woolie Committee member

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    full text at scihub: https://sci-hub.cc/10.1097/PSY.0000000000000512

    Let me share with you the author list for this study:
    That lightbulb sure must have been tough to change, eh?

    The primary result is that there were no significant differences between groups in microbiome diversity, contrary to their predictions.

    The forest thing they did (Variable Selection using Random Forests), trawls through a large dataset to find variables that reliably distinguish your two groups. If you have a large enough set of variables, you are pretty much guaranteed to find something with this approach. So you can't really conclude anything from it. All you can use it for is to generate a hypothesis to test on your next set of participants. They also tried to do various confirmatory analysis of the variables after they had dug them out, but they've used correlation, which doesn't seem to me to be the right approach when you have two groups that are strictly delineated.

    Still, at least they were honest about their predictions not being confirmed. They could have done what a lot of their colleagues done, and re-written the intro to make their predictions fit with the findings.
     
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  5. Adrian

    Adrian Administrator

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    Random forest techniques are quite a popular classification technique in machine learning.
     
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