# Questions tagged [inventory]

For questions about mathematical models and algorithms for optimizing inventories.

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### Confusion about how to account for leadtimes with a fixed-review period base stock(S,T) inventory policy

So we're using a fixed review period model with base stock $S$, and review period $T$ of 1 month - the period is not chosen optimally to minimise ordering cost like in an EOQ model, it's just a nice ...
80 views

### Relation between order quantity and average cycle stock

Annual demand: $1000$ units Unit cost: $5$ dollars Company replenishes the inventory two times per year. Average Cycle Stock: $300$ I am asked to compare average cycle stock with number of ...
145 views

### Generating numbers that should add up to a fixed value while they follow a known distribution

Suppose a perishable item that is associated with a shelf life $m\in \mathcal{M} = \{1,\dots,M\}$. We have a periodic review system with stock level $S$, i.e., based on the inventory level of the item,...
568 views

### Recommendations for OM blogs

Could someone suggest good blogs to follow for researchers in Operations Management/ Supply Chain Management /Operations Research?
30 views

### If $F$ is MHR (log-concave), can the monopoly reserve price exceed the mean?

Let $V\sim F$ be some positive valued random variable such that $F$ has a monotone hazard rate (alternatively $F$ is log-concave). Let $p = \operatorname{argmax}q(1-F(q))$. We call $p$ the monopoly ...
18 views

### Lead time higher than cycle time in static EOQ model

All the examples I saw so far were for the case when lead time is smaller than the cycle period. What should the reorder point be if lead time is higher than the cycle time? Should I just simply order ...
85 views

### inventory control for vending machine like mini store

Let's say we have a kiosk inside gas station selling cigarettes and snacks outside a supermarket. There are limited space for each product. The kiosk only allows to get restocked from the supermarket, ...
99 views

### Safety Stock with Fill Rate Criterion

When applying the base stock inventory policy, assuming the daily demands are normally distributed with parameter $(\mu, \sigma)$, we can find the optimal parameter $S$ (the base stock level) in ...
41 views

### Concepts for managing inventory and orders with specific fulfillment date

I'm modeling a fairly basic order and inventory management system but with a use case that doesn't seem very common (or at least hard to look up online and in books about operations): the order ...
342 views

### Safety stock for log-normal distribution demand

I came across this example on how to model your lead time demand as a log-normal distribution and calculate the safety stock. https://www.linkedin.com/pulse/why-you-keep-missing-your-service-level-...
131 views

### Scaling of standard deviation for forecast error

I am doing inventory optimization for my firm and need to compute the safety stock for a couple of products. I have learned that the correct quantity to consider in calculating the safety stock is the ...
172 views

### How to form math model to solve this problem using cplex

Hiring company has the following requirement within a year; week 1 to 5: 20 week 6 to 20: 40 week 21 to 40: 35 week 41 to 60: 55 week 61 to 80:75 week 81 to 100: 60 Training time for an ...
100 views

### Safety stock calculation with production forecast variance

I am trying to find an safety stock calculation where the expression incorporates: Lead time variance Sales demand variance & Production forecast variance My calculation so far is based on the ...
101 views

### How to calculate Cycle & Safety Stock

I have been asked to calculate cycle and safety stock levels for one of our business units. I have very little/no knowledge on the subject of inventory theory so would like to ask what a reasonable ...
85 views

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### Which EOQ-based $(r,Q)$ approximation has a fixed worst-case error bound?

There are two common approximations for the $(r,Q)$ inventory optimization problem that use the EOQ model. It is well known that one of them has a fixed worst-case error bound, but there is confusion ...
Here is a typical setup for the newsvendor problem: The newsvendor buys newspapers for $c$ each, sells them for $r$ each, and salvages unsold newspapers for $v$ each. The demand distribution has ...