# Question regarding online bagging (bootstrap)

1. Mar 17, 2012

### cc2709

Hello guys,

I'm trying to understand the proof of convergence for online bagging/bootstrap, in the Oza's paper an expression says:

θ ~ $\sum$$^{N}_{t=0}$P(Poisson(N)=t)Multinomial(t,1/N)

θ may represents a vector with each element being a real value;
Poisson() is the Poisson distribution;
t is certain real value;
Multinomial() is the multinomial distribution...

But I am totally lost when put all these stuff together
what's that mean by adding up the multiplication of a probability with a distribution?

I don't have a solid background on probability and I've been tortured by these for a while...hopefully I can get some suggestion...