A measure of the size of an effect in a population is called EFFECT SIZE.
The principle of effect size is used in statistical study of data obtained in experimental research. In research studies which compare different interventions, effect size refers to the magnitude of the difference between population groups that are been considered.
You can see how old people are
Geological change will not cause a mass extinction, because it happens on a too big scale - on the scale of millions of years. During such long time, it is more likely that other causes will influence the survival of extinction of species, such as climate change or environmental disasters, and even if there is a small influence, it would not be significant next to other causes.
