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What does fold change mean?

Discussion in 'Health News and Research unrelated to ME/CFS' started by Sarah94, Sep 13, 2019 at 12:32 PM.

  1. Sarah94

    Sarah94 Senior Member (Voting Rights)

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    If a research study describes something as having a 0.6 fold change. Does that mean it is higher or lower?
     
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  2. lansbergen

    lansbergen Senior Member (Voting Rights)

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    That must be in the paper.
     
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  3. strategist

    strategist Senior Member (Voting Rights)

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    The number n, after a 0.6 fold change, is n * 0.6
     
  4. Trish

    Trish Moderator Staff Member

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    Can you give an example of a paper that has said that?

    As strategist says, I would assume it would mean that the thing being measured multiplied by 0.6, so it is 60% of what it was before - in other words it is lower. If someone weighs 100kg and their weight undergoes a 0.6 fold change, they would weigh 60kg.
     
  5. Barry

    Barry Senior Member (Voting Rights)

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  6. Jonathan Edwards

    Jonathan Edwards Senior Member (Voting Rights)

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    I don't think this is at all clear. A 0.6 fold change could be a change to 60% or to 166% or even to 160% or 40% as far as I can see. Nobody normally says this. Unless it is some special technical term in a particular area it sounds like half-baked usage.
     
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  7. Trish

    Trish Moderator Staff Member

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    There is a Wikipedia page on it!

    This suggest the most common use is as a multiplier, so if the number fold is less than one, it's a decrease:

    ''More ambiguous is fold decrease, where, for instance, a decrease of 50% between two measurements would generally be referred to a "half-fold change" rather than a "2-fold decrease''
     
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  8. Jonathan Edwards

    Jonathan Edwards Senior Member (Voting Rights)

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    But a tenfold change can be to 10%. We often say change by an order of magnitude - when it is already assumed which way.

    They probably mean change to 60% but why not say so? We normally say a 40% decrease.
     
  9. Forbin

    Forbin Senior Member (Voting Rights)

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    Never having had any occasion to refer to a fold change in real life, for a long time I assumed it was 2^x, where x was the number of "folds," as in folding a piece of paper equally. So, three fold of something would be 8 times the original, because, in my mind, if you folded a piece of paper equally 3 times you produced 2^3 subdivisions, i.e. 8.


    Sigh. Another beautiful hypothesis slayed by an ugly fact. :)
     
  10. shak8

    shak8 Senior Member (Voting Rights)

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    Start at zero, or baseline of whatever you are testing about.

    "Fold" means x or multiplied by x.

    So starting at zero, increase by 0.6x.
     

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