How to predict forecasts from shipment history and through causal factors?

Summary:

Business user wants to predict the forecast if they enable any causal factors. They want to know the quantity or increasing the percentage of forecast if we add any holiday causal factors.

and also they wants to predict the forecast which is decomposed from shipment history.

Could you please help to predict forecast from shipment history and through causal factor?

Content (required):

Need to predict percentage of forecast generation from shipments history and Causal Factors

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