Questions tagged [operations-research]

uses mathematical and statistical methods to improve efficiency

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20 views

Minimum number of stores-set cover problem in R [on hold]

I have a list of n products that I want to buy. Also, I know k stores and the availability of products that I want to buy on these stores. I need to find the minimum number of stores to satisfy the ...
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1answer
42 views

Simulating a queue in R [closed]

It's noted that the number of folks in a stationary system will maintain an average equal to the rate of arrival multiplied by the mean of the service distribution. Where the formula $L = \lambda$ ...
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45 views

How to handle real-world (soft) constraints in an optimization problem? [closed]

I am working on a problem which involves optimizing for minimum power consumption in a large compressor network interconnected through pipelines (think of a connected graph with nodes as compressors ...
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8 views

qualitative data in data envelopment analysis (DEA)

I wish to use qualitative input to calculate efficiency using DEA model. For that I based the input on certain questions which were answered on 1-5 rating scale. each input has 5 such questions(...
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51 views

Which optimization algorithm applies better for this production problem? Cost minimization

This is a cost minimization problem, where I have to plan the development of a field and the installation of some machines there. Rectangles A,B,C,D represent production areas, that can overlap. I ...
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1answer
32 views

How many people at any given time

I have been tasked with finding out approximately how many people were in a location at a given time. I know how many people arrived per hour and how many people left per hour and the average time ...
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1answer
77 views

Assignment Problem (Linear Programming, Genetic Algorithm, etc.)

I'm looking for advice on how I should approach a specific problem. Some background first: The problem is about shipments falling into a bin. There are 19 such bins, which are further sorted into 20 ...
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1answer
98 views

Monte Carlo simulation--Have I applied Bernoulli distribution properly? [closed]

I am trying to run a monte carlo simulation and I just wanted to make sure that I set it up properly. A salesman visits 100 different homes. Someone answers the door 80% of the time. Of that ...
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1answer
40 views

Sample size human sciences [closed]

I will apply a questionnaire with 90 questions about the possible requests: very bad, bad, neutral, good and very good, the answers will be categorized into 8 different groups. Subsequently the data ...
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1answer
61 views

Office Desk Rota Assignment problem

This is not a home work and the question is not related to studies (I am not a student). I have to do the weekly desk rota at the office and thought this forum might help with suggestions. My problem ...
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1answer
61 views

Is this a contextual bandit problem?

I have an operations research problem that I would like to solve but I am unsure what the correct framework for analyzing it would be. The closest I've come across so far is contextual bandits I ...
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25 views

How can we decompose generalization gap as done in the paper “Generalization in Deep Learning”?

I am reading a recent paper "Generalization in Deep Learning" and I am unable to understand a step. In this step, they first take neural network as a direct acyclic graph(DAG) and described output of ...
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117 views

How to deal with NaN when they make up 45% of the data?

I compare two countries (Germany and Sweden) and have 30 variables over 15 (2001-2016) years. Unfortunately, the first years (2001-2007) for Sewden and (2001-2006) for Germany have NaN (missing values)...
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1answer
122 views

Design of experiment: Is there correlation between performance vs. employee attrition?

Background: Assume company X has a cyber security incident team. One of their key performance/risk indicators is how fast they triage the security incidents. For the past 2 quarters, COO observed ...
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29 views

stochastic inventory question

Does anyone have any references for inventory optimization? By optimizing I mean going from supplier to the allocation to the store. I am doing research as to how to optimize any given inventory ...
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1answer
890 views

What is the difference between the Poisson distribution and the uniform distribution?

I'm modeling a factory with orders arriving independently of each other. I need a series of actual time stamps of arrivals. I've been told that everyone uses the Poisson distribution to model arrivals....
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22 views

Does anyone here knows this variable? No one had ever answer this yet in all sites I've been. [duplicate]

what does "W" represents there in the equation 2? no one had ever answer this yet in all sites I've been. here is the source. http://www.scirp.org/journal/PaperInformation.aspx?PaperID=65933
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1answer
1k views

What concepts in optimization do I need for machine learning?

I am a Math/CS dual major. As part of my math major, I have the option of taking optimization and mathematical programming classes. I am also interested in machine learning. I know that a lot of ...
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42 views

Discrete optimisation of a gym workout routine

I am working on the following problem, which I would like to solve using an elegant optimisation method (both because the answer is genuinely useful to me, and because I am interested in the maths of ...
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1answer
11k views

If the mean is equal to the standard deviation, what is the general likelihood that the underlying distribution is normal vs exponential?

This comes from operations analysis. Often you have measurement of times, such as time between customers arriving at a store (e.g. Starbucks) or time it takes to process an order (e.g. a cappuccino). ...
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10 views

Same group, different variance (4 variables) preoperation, 1 month post op, 6 months, 1 year

Pain score of same group, Preoperation, 1 month post operation, 6 months post operation, 1 year post operation. What design of analysis should I use? From research I have came to the conclusion (not ...
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2answers
3k views

Why do Statistics, Machine learning and Operations research stand out as separate entities

It seems nowadays people who work in ${\bf Statistics, \ Machine\ Learning \ and \ Operations\ research }$ all consider themselves as working in data analytics. These three categories try to ...
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128 views

How to optimize call center call times?

I have been asked to develop a predictive model to optimize call times from a call center. We have historical data on successful calls, date/time, member-specific attributes, etc. Ideally, the output ...
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28 views

Comparing coefficients to understand the change in impact of a variable

Our success measure (satisfaction) have dropped in July compared to June. I want to understand the factors that affected the drop. Since I could not create a flag that identify records that ...
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114 views

Inbound/Outbound calls integer programming

For modeling on call center schedule optimization with inbound calls, I can use library(lpSolve) from R to get the solutions by ...
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0answers
72 views

effect of linear term on quadratic programming

What's the impact of linear term ($d$) on quadratic programming problem ($P$) described as follows \begin{align*} \min_x d^T x + 1/2 x^T D x\\ \text{such that }A^T x \geq x_0 \end{align*} where $D$ ...
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1answer
21 views

What type of test / research design is recommended for this analysis

It is assumed that people are not seeking for help when they need to, therefore a program is implemented to teach them when to seek help. People can join the program voluntarily. I would like to study ...
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1answer
435 views

Reverse Code for Factor Analysis

I have done my survey, and now I need to do the data analysis. However, I am not sure whether or not I need to do the reverse code at the first step before I can do the remaining analysis. There are ...
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74 views

Modeling worker performance parameters for optimum allocation of tasks to workers

Lets say we have an English to French translation task in a company and there are 100s of workers who are proficient in doing this task but each worker has its own unique attributes which allow them ...
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1answer
62 views

Sample size for clinical research

I determined the sample size already (25), but I want to know if it has to be increased because of a minor change. Our study consists of two groups - one will be sedated and the other will not. For ...
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288 views

online bin packing and machine learning

I am trying to optimize scheduling disk allocation in data centers. In nature it is an online bin packing problem. But, since each customer has it's own behavior or kind of workload I was wondering, ...
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108 views

A YouTube View Estimator

Here's a thought experiment that I can't come up with a good answer for. Imagine you have 5 YouTube videos that you want to reach 50,000 views (10,000 views per video) by the 10th day after ...
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1answer
3k views

Constrained assignment problem (Linear Programming, Genetic Algorithm, etc…)

I'm looking for advice on how I should approach a specific problem. I have about 1000 shops that I have to assign to about 20 different supply centers out of a possible 28, and I'm trying to pick the ...
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255 views

Scheduling Algorithm for a multi-server queue problem

I have 4 servers, n customers and m reports. At any time, a customer may request one of m reports. There are only 4 servers which are capable of generating reports. Each server can only process one ...
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1answer
128 views

How to include 29 colleges as an independent variable in logistic regression

I am working on a model that predicts gestation period of new hires. By gestation period, I mean the period between when they completed their training and the time they start working on their first ...
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1answer
1k views

Convert maximization problem to minimization

I am looking at the derivation of the Maximal Margin Classifier model, where they typically transform the following maximization problem: into this minimization problem: Why is maximizing $\frac{1}{\...
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110 views

An algorithm for pairing

I want to divide $2n$ objects into $n$ pairs according to the Euclidean distance between them, however, I am not sure which algorithm I should use. Should I use one of matching algorithms?
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1answer
241 views

Designing a Simple (a.k.a 'bad') Ranking value from several values of unknown distribution

I am but a humble developer, so please forgive if I butcher terminology of confuse concepts. I am looking at designing a simple ranking of Average Internet Audience Rank based upon a bloggers ...
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1answer
106 views

Statistically back-calculating: Markov Chain?

I would like to calculate the value of bacteria on 4 surfaces $i=\{1..4\}$. A person touches some of those 4 surfaces at random and a count is made on their finger after each surface contact ($x_i$). ...
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4answers
6k views

Operations research versus statistical analysis?

What is the difference between operations research and statistical analysis?