= Growth factor
{title2=$g_i=Q_i/Q_{i-1}$}
For positive quantities measured at successive steps, the growth factor $g_i=Q_i/Q_{i-1}$ is a <dimensionless> <ratio>. It can be below one when the quantity shrinks. Repeated <multiplication> gives $Q_n=Q_0\prod_{i=1}^n g_i$, so the common factor that reproduces the endpoint after $n$ identical steps is their <geometric mean>. A factor $g$ corresponds to a relative change $g-1$; factors must be averaged before subtracting one when summarizing compounded change.
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