If a research study describes something as having a 0.6 fold change. Does that mean it is higher or lower?
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.
This seems to explain it: https://www.researchgate.net/post/what_fold_change_resistance_factor_tells_about_drug_resistance ETA: Just realised I missed the point! A 2-fold change is a 2x, or 2 times, change. Replace 'fold' for multiply sign. As others have said above. I was thinking there was something medical-speak about "fold change" .
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.
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''
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.
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.
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.
