Buildup forecasts are predictions that go from the specific to the general, or from the bottom up. If you have sales reps, ask them to project the next period’s sales for their territories and to justify their projections based on their anticipated changes in the situation.

Then combine all the sales force’s projections to obtain an overall figure.

If you have few enough customers that you can project per-customer purchases, build up your forecast this way. You may want to work from reasonable estimates of the amount of sales you can expect from each store carrying your products, or from each thousand catalogs mailed.

Whatever the basic building blocks of your program, start with an estimate for each element and then add these estimates up.