Tag Archives: Asymptotics

Convergence in probability and the limiting behavior of moments: A useful (elementary) reminder

 Convergence in probability is a stochastic analog of the convergence of a sequence of numbers. Hence, a sequence of random variables Y_n converges in probability to a constant c  i.e.

Y_n \rightarrow^P c

if \forall \epsilon >0

P ( |Y_n - c | < \epsilon ) \rightarrow 1 as n \rightarrow \infty

which suggests that for n sufficiently large Y_n will be sufficiently close to c.

 

 

Note that by the Chebychev inequality we get that the sufficient condition for Y_n \rightarrow^P c is that Y_n tends to c in quadratic mean i.e.

E(Y_n-c)^2 \rightarrow 0

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