Forecasting with irregular dates

When I modelled Rate as a function of Interval I obtained the following. Using a prediction of INTERVAL using it's past this equation can then predict rate , which can the be used to predict demand. This kind of model allows autoregressive structure in rate to be incorporated as well as allowing for Pulses , Level Shifts and/or Local Time Trends in rate.

MODEL COMPONENT LAG COEFF STANDARD P T
# (BOP) ERROR VALUE VALUE

Differencing 1
1CONSTANT .295 .840E-01 .0246 3.51
INPUT SERIES X1 INTERVAL

Differencing 1
2Omega (input) -Factor # 1 0 .685E-01 .346E-01 .1193 1.98
INPUT SERIES X2 I~P00002 12/03/11 PULSE

Differencing 1
3Omega (input) -Factor # 2 0 1.43 .168 .0010 8.52
INPUT SERIES X3 I~P00007 12/08/11 PULSE

Differencing 1
4Omega (input) -Factor # 3 0 -.935 .168 .0051 -5.57
INPUT SERIES X4 I~P00010 12/11/11 PULSE

Differencing 1
5Omega (input) -Factor # 4 0 1.37 .260 .0062 5.27