Straight-line Method. How To Estimate Demand for a New Product. By partnering with a 3PL like ShipBob, you can access advanced analytics and distribution metrics to make the process much easier. Refer to the most popular method of demand forecasting. ");}}else if(elem.type=='checkbox'){var elems=form_to_submit.elements[elem.name],found=false,err=[];no_error=true;for(var i=0;i'));}}else if(elem.tagName=='SELECT'){var selected=true;if(elem.multiple){selected=false;for(var i=0;i