The phrase "considerable heterogeneity" means that there is a significant amount of variation or diversity among the individuals or things being discussed. Full definition
Patients displayed considerable heterogeneity in their ratings of health states relative to death... but significant percentages of patients rated each evaluated state of serious functional debility as equal to or worse than death. (firstthings.com)
Although measurements at the wetland - air interface displayed considerable heterogeneity, the air samples show that the methane emissions rapidly mix just above the surface, creating a uniform regional carbon - 13 isotopic signature of − 71 ‰ ± 1 ‰. (eos.org)
In untracked classes, where there is considerable heterogeneity of performance, students learn less if their peers are lower performing. (educationnext.org)