# Definition:Time Series/Origin

## Definition

The origin of a time series is an arbitrary timestamp of an observation which is chosen in order that all other timestamps can be measured from that origin.

This timestamp is often denoted $\tau_0$.

## Sources

$1$: Introduction:
$1.1$ Four Important Practical Problems:
$1.1.1$ Forecasting Time Series
Part $\text {I}$: Stochastic Models and their Forecasting:
$2$: Autocorrelation Function and Spectrum of Stationary Processes:
$2.1$ Autocorrelation Properties of Stationary Models:
$2.1.1$ Time Series and Stochastic Processes: Time series