Random walk with a drift or AR(1)

[rcaus]

Hi hubbers,
The first equation is the AR(2) model whilst the second model is taken to be random walk with a drift.
xt = b0 + b1x(t−1) + b2x(t−2) + åt
xt = b0 + b1x(t−1) + åt
For the second model why can’t we say it’s an AR(1) model instead of random walk with a drift.
Can someone help me out as most likely I wrote the wrong equation for the second model.
Regards
rcaus

 

[rus1bus]

Random walk is still an AR model, except that the value of b1 is 1.
Special characters in above equations have not come out properly, but your equation for Random walk with drift model looks fine otherwise.