is 5 fold the same as 5 times
Fold change is so-called as it is common to describe an increase of multiple X as an ``X-fold increase''. As such, several dictionaries, including the Oxford English Dictionary and Merriam-Webster Dictionary, as well as Collins's Dictionary of Mathematics, define ``-fold'' to mean ``times,'' as in ``2-fold'' = ``2 times'' = ``double.'' Likely because of this definition, many scientists use not only ``fold'' but also ``fold change'' to be synonymous with ``times'', as in ``3-fold larger'' = ``3 times larger.''. 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''.
Fold change