[alyaae]

Since the WIP is overestimated, therefore:

Before the correction;
WIP increases, cost per EU decreases (because there are lot of WIP in there, so the total cost divides by EU will give you less amount of cost per EU), thus, total cost of output decreases

Correction;
WIP decreases, cost per EU increases, thus, total cost of output increases

[Author]

Posts