# the difference between non-stationary data and random data?

#### Fred_a

##### New Member
what are the the difference between non-stationary data and random data? If we detrend a stationary data and make it non-stationary what will happen, will it be random?

#### BGM

##### TS Contributor
Conceptually very different term.

A simple example: consider a sequence of i.i.d. random variables $$X_t$$ with finite mean and variance. Then it is a stationary time series. Next if you "integrate" it to form a random walk, i.e. $$Y_t = Y_{t-1} + X_t$$, then it is not a stationary time series. But both are random, right?