Statistics: rarefaction curve

Self-tutoring about statistics: the tutor mentions rarefaction.

I’ve seen the terms rarefy, rarefied, rarefaction, etc, but never knew what they meant. Today I decided to change that, but it was like opening an overfilled closet where everything jumps out at you. The word family of rarefy includes some pretty technical, rarefied defnintions.

A rarefaction curve is used in ecology to predict species encounters. Essentially, it’s an average of how many species you encounter (y axis) versus the effort you put in (x axis) or else how many total individuals you encounter (also x axis).

Whichever x dimension you use, be it individuals encountered or effort, the species encountered will rise more steeply at first but will start to flatten out. The rarefaction curve is the average of several such curves, and its smooth trend is used to predict the asymptote – the total number of species you would encounter if you spend virtually infinite effort exploring the area, or else discovered all the individuals living there.

Rarefaction curves, in a larger sense, can be used to predict when a diminishing return is no longer worth pursuing.

I’ll be talking more about the allies of the word rarefy.



Rob K Statistics

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

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