The sensitivity analysis related with the cost parameters is shown in Fig. 5. The overall objective of SN is to
minimize the total delaying cost. However, there are trade-offs between delaying cost and the others, especially
the transportation cost tries to tolerate the delaying cost even using more expensive transportation modes.
While the unit delaying cost is decreasing in steps of $1, the delaying cost and transportation cost (between
suppliers and warehouse) start decreasing together after a decrease of $3.
The last sensitivity analysis is related with starting inventory parameters of the model. The aim of this analysis
is to show the relation between warehousing cost and delaying cost. Increasing the starting inventory levels
in warehouse will ensure to reach manufacturer faster and thanks to that, delayed product quantities and
related cost will decrease but warehousing cost will increase. This situation can be seen in Fig. 6. Because the
unit cost of the holding inventory is lower than delaying cost, a reducing is realized in total cost function.
However, after an increase of 400–450 pallets in the starting inventories, intensity of the reduction in total cost
is getting insignificant.