Question

ARIMA (1,0,0) is equivalent to _____________

Answer 1

ARIMA(1,0,0) = first-order autoregressive model: if the series is stationary and autocorrelated, perhaps it can be predicted as a multiple of its own previous value, plus a constant.  The forecasting equation in this case is

Ŷt  =  μ  +  ϕ1Yt-1

…which is Y regressed on itself lagged by one period. This is an “ARIMA(1,0,0)+constant” model.  If the mean of Y is zero, then the constant term would not be included.