Fig. 1

Monotonic and non-monotonic volume decline using ATN. A An illustration of monotonic GM volume decline as hypothesized when following the ACH hypothesis using ATN groups. B A permutated order of the upper case that clearly not shows a monotonic volume decline. A temporary volume increase causes large residuals that cannot be explained by a monotonic model. Therefore, the pathway in A would be preferred over B (“higher evidence for monotonic decline in A”)