Explain Box-Jenkins intervention analysis.

Box-Jenkins Methodology
PHASE  I : Identification and Preparation

1. Data Preparation 

Differencing the data to achieve stationary series

Transform data to stabalize variance

1. Model Selection/identification

Shortlist suitable models according to the data

Apply ACF and PACF to determine potential models

PHASE  II : Estimation and Testing

1. Estimation

Estimate parameters in potential models

Select best model using suitable criteria

1. Diagnostics

Check ACF/PACF of residuals 

Do portmanteau test of residuals

PHASE  II : Forecasting/Application

Using the derived model to forecast future series