Dictionary:Expectation

1. An operator that denotes the mean, or weighted mean where values are not equally probable. Usually denoted by braces, $E\{\ldots \}$.

2. In seismic processing usage, it indicates the sum of elements for finite wavelets $\left(b_{t}\right)$, or the mean of an infinite time series $\left(u_{t}\right)$:

$E\{b_{t}\}=b_{1}+b_{2}+b_{3}+\ldots +b_{n}$, or

$E\{b_{t}\}=\lim _{n\to \infty }{\frac {u_{-n}+u_{-n+1}+\ldots +u_{0}+u_{1}+u_{2}+\ldots +u_{n}}{2n+1}}$