Rather than to determine a structural break by nature of economic volatility (or test not to determine itself) i want to evaluate the results of a sudden change ( a break) in an explanatory variable on dependent variable that how long this effect will sustain ? I study permanent income hypothesis and i need a specific structural break that sudden changes in the average expected permanent income causes long term effects on household´s consumption.How i can specify this break in the model without general tests that shows stems of the break is reflected on constant or trend ?