All things do not remain equal or the same, therefore, other exogenous variables or factors can — and will — often come into play. (fastgraphs.com)
When it doesn't, they blame exogenous variables and the foolishness of other market participants. (valuewalk.com)
In some cases, they have attributed inter - or intra-population variability in mating effort to exogenous variables such as pathogen prevalence [63]. (rsos.royalsocietypublishing.org)