What is chance variation in statistics?

What is considered chance variation in statistics? Thank you!

What is chance variation in statistics?
Apparently Jim Bo knows nothing about statistics so he copies something from a text or class notes.


Let me see if I can explain it in layman's terms:


When an experimenter designs and runs an experiment, he/she tries to control as many of the outside influences as possible to focus on the main variable(s) of interest. If an outside variable(s) cannot be controlled there are techniques for "blocking" these variables. But all variables cannot be controlled or blocked, and these contribute to random, or chance, variation in measurements.
Reply:. Stat is so full of Crap, you shouldn't concern yourself with this. Statisticians can manipulate figures so much, they need fancy terms to hid that fact.


"...Chance variation, chance error.


A random variable can be decomposed into a sum of its expected value and chance variation around its expected value. The expected value of the chance variation is zero; the standard error of the chance variation is the same as the standard error of the random variable---the size of a "typical" difference between the random variable and its expected value. See also sampling error. " ...


... They use the word 'error' as though it were a badge of honor! The major 'error' WE can make is to trust their figures and conclussions!