random varriation

I wish you would say which topic you were referring to :-) I assume it is in relation to time series analysis. Random variations are (by definition) variations that occur at random and therefore cannot be predicted. Forgetting all other reasons for variations, even if sales (for example) were increasing in a nice smooth pattern, nothing in life is perfect and so some years sales might be a bit lower and some years a bit higher than expected - these are random variations that occur for no specific reason and therefore cannot possibly be predicted.

Thanks sir john..Now I understood completely thanks for your explanation....

In short,can we say that random variation is a variation that occur anytime or it cannot be predicted??

Yes :-)