Joe Barnes is the owner of Standing Tall, one of the major roofing companies in town. Much of the company's business comes from building roofs on new houses. Joe has learned that general contractors constructing new houses typically will subcontract the roofing work about 2 months after construction begins. Therefore, to help him develop long-range schedules for his work crews, Joe has decided to use county records on the number of housing construction permits issued each month to forecast the number of roofing jobs on new houses he will have 2 months later. Joe has now gathered the following data for each month over the past year, where the second column gives the number of housing construction permits issued in that month and the third column shows the number of roofing jobs on new houses that were subcontracted out to Standing Tall in that month.

Use a causal forecasting approach to develop a forecasting procedure for Joe to use hereafter.