# Tag Info

Accepted

• 32.7k
Accepted

### Loss functions for specific probability distributions?

There is indeed a paper titled Loss Distributions that provides the limited expected value functions $L(x)$ for several probability distributions (on page 15). It is directly related to the first-...
• 5,412

### Modeling the uncertainty of the input parameters

In reference to the first question, I think it often comes down to the information you have about the underlying uncertainty. If you only have intervals or ranges, robust is the way to go. If you have ...
• 1,317

### Modeling the uncertainty of the input parameters

The following papers discuss this extensively with numerical experiments, but they tackle specific examples. Emphasis is mine. Kazamzadeh et al. (2017) This is a comparison of the two techniques using ...
• 5,412
Accepted

### Modeling the uncertainty of the input parameters

Regarding your first question, I think other answers have summed it up pretty good. Two things I would add are as follows: Stochastic programming models (besides chance constraint/probabilistic ...
• 2,463
Accepted

• 13.5k

### Model or State Uncertainty in Queueing Model due to uncertain arrival rate

After having read Chapter 5.3 of Decision Making Under Uncertainty by Mykel J. Kochenderfer, I have come to some conclusions. We are dealing with model uncertainty, in which case we can formulate a ...
• 463

I tried simulating lots of normally distributed lead times and the normally distributed demand in each. The lead time demand sure looks normal: But a normality test gives $p = 0$ to at least 9 ...
• 13.1k

### How to calculate Cycle & Safety Stock

Cycle stock is used to meet the mean demand. Safety stock is used to protect against randomness in demand. So, I would use your historical data to calculate the mean demand over time and the inventory ...
• 13.1k

### What is the meaning of monotone hazard rate (MHR) distribution?

For a Poisson process the rate of events is constant. The distribution of time between events in the Poisson process is exponential with $F(v)=1-e^{-\lambda v}$ for $v\ge 0$ which gives the hazard ...

### Binary variable to indicate zero probabilities

You are going to bump into a limitation of finite-precision floating point arithmetic. Basically, a small enough probability value will be indistinguishable from rounding error. Assuming you are using ...
• 39.5k

I've thought about this for a bit, and I now believe that leadtime demand in most common situations is not normally distributed, although it may be as usual a good approximation. Of course, we know ...
• 1,542

### Question about a queueing problem

This is a $M/M/1$ queue with Poisson arrival distribution with $\lambda =1/10$ and Exponential service distribution with $\mu=1/3$. The proportion of the time that the system is busy can be calculated ...
• 8,667

### Modeling the uncertainty of the input parameters

Stochastic Optimization (SO) requires the probability distributions (PDF) of the uncertain variables which are usually hard to fit. Then, a large number of scenarios are required to be sampled from ...

I have done extensive analysis of procurement lead time distribution across industries. In my experience, I found most of the distribution are heavily skewed towards the left. Yes, you are right! ...
• 81
Accepted

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

I'm still not sure I understand the question, but I'll suggest an answer to what I think is being asked. I'm going to assume that an a priori upper bound $O$ exists for $o_t$. To keep what follows ...
• 39.5k

### What is the hazard-rate of a truncated probability distribution?

The blog entry Defining Hazard Rate at a Point Mass. "Applied Probability and Statistics in Actuarial Science and Financial Economics", contains what is needed to answer the question. Define ...
• 13.5k
1 vote

### Queuing theory question

This is $\ M/M/1/\infty/\infty\$ queue model. The symbols in turn represent: The distribution of the time between successive customer arrivals is negatively exponential The distribution of hours of ...
• 197
1 vote

### Optimizing Safety Stock in a Multi Echelon Optimization

If you would like to take into account the inventory model directly in an optimization model, your problem is more likely classified in the following areas: Multi-Depot Location Routing Problem ...
• 8,940
1 vote
Accepted

### lsqcurvefit error in simulation of demands in MATLAB

My professor helped me for solving this error like below: ...
• 55
1 vote

### How to calculate Cycle & Safety Stock

Safety stock for a demand stream (assuming it is normally distributed without recurring lumpiness) depends on a number of factors: Target service level Demand accuracy Lead time Supplier reliability ...
1 vote

### Queuing models in R, $\lambda$ Little

So far this is what I have come up with lambda <- 2 interarrivals <- rexp(5000,lambda) ## (2 items per minute) Provided the $\mu$ we expect that the ...

Only top scored, non community-wiki answers of a minimum length are eligible