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Reviewer #1: Yes
Reviewer #2: No
We include the data and all of the statistical analysis in this link https://doi.org/10.6084/m9.figshare.14444609.v1 . Also we include the lingo models in https://doi.org/10.6084/m9.figshare.14450430. Both the data and the lingo models could be used to replicate the results.
2. Has the statistical analysis been performed appropriately and rigorously?
Reviewer #1: Yes
Reviewer #2: No
We include the data and all of the statistical analysis in this link https://doi.org/10.6084/m9.figshare.14444609.v1 , and could be used to replicate the results
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Reviewer #1: Yes
Reviewer #2: Yes
We include the data and all of the statistical analysis in this link https://doi.org/10.6084/m9.figshare.14444609.v1 . Also we include the lingo models in https://doi.org/10.6084/m9.figshare.14450430. Both the data and the lingo models could be used to replicate the results.
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Reviewer #1: Yes
Reviewer #2: No
We review our article with a native American speaker and we correct the typographical
o and grammatical errors
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Reviewer #1: Thank you for inviting me as a reviewer for the paper titled Production
planning of a furniture manufacturing company with random demand and production capacity
using stochastic programming. The paper has well structure. The strengths of this
paper are an interesting topic and good methodology.
However, the authors need to consider the following minor/major points as a limitation
or further scope for refining the paper:
- Clearly define motivations for this study.
The motivation is defined in the first paragraph of the introduction “This work presents
an aggregate plan that was made for a company that manufactures furniture in the State
of Hidalgo. Initially, a first approach to the solution of the problem was made in
[1]. In this work, only the production capacity was considered as a random variable
using two models, one with a continuous probability distribution and the other with
a discrete one. However, another extremely important random variable had been ignored
due to complexity: demand. Therefore, the motivation for this work is to improve productivity,
have efficient policies to manage its production and minimize production costs, developing
models of aggregate production plans (APP) with uncertainty due to a real need of
a furniture company, Models are considering real characteristics such as human factor,
multi-period production criteria and service level policy due to the use of backlogs”
- Need to highlight the novelty of the study in the introduction.
The novelty is in the third and fourth paragraphs :
“The novelty of this work could be summarized in five points,1) this study provides
a mathematical programming model that has been adapted for real needs of a company,
which incorporates a service level constraint that it is not found in the literature,
usually a confidence percentage is used (which could turn the problem into a chance
constraint programming. 2) In the literature only the expected value of the objective
function is reported (here and now solution) with the history of the process considered,
that is, with the nonanticipativity constraints or the value of the expected objective
function. If these constraints are removed, the wait and see solution appears, in
our research, both solutions are reported, also the absolute difference of the two
solutions is reported, called the expected value of perfect information that could
help the company to deal with uncertainty in economic decisions. 3) An extensive sensitivity
analysis is carried out, varying the cost parameters, the percentage of the service
level and varying the parameters of the probability distribution of uncertainty. Few
studies carry out a sensitivity analysis, but in our knowledge, nobody analyzes the
impact of service level and varies the parameters of the probability distribution.
Through this sensitivity analysis, interesting results were obtained, for example,
that the total cost of the APP goes down, when the variability of the production capacity
(standard deviation of the probability distribution) is reduced. 4) Due to the complexity
of the problem, the software could not solve the problem satisfactorily for a fourth
period, finding a solution that is only feasible, then, a second model is developed
using discretization of the probability distribution, it has been shown that if the
distances of both distributions are minimal, the solution found is closer than the
true optimum the quality of the proposed model is presented in the results, where
both models are compared.
Finally, 5) a methodology to deal with problems using stochastic programming is proposed,
although it was applied to the case of this APP, can be implemented in other areas
of industrial engineering sciences, such as supply chain networks, problems of vehicle
routing, design, and redesign of layouts, among others. Advantages and disadvantages
are detailed in the conclusions section. Table 1 shows a comparison between some relevant
studies in the area and our study, so that the novelty and contribution of our proposal
can be observed.”
- The Methodology section adds a figure, which describes the stages and steps in applying
the presented methodology.
We improved this figure (Fig 2: Flow Chart of the Methodology)
- Literature analysis needs to be improved. In the entire paper, there is only one
cited paper from 2019, while from 2020 and 2021 there are no papers. Add another 10-15
papers of more recent date (period 2019-2021), such as:
o Giri, B. C., & Dey, S. (2020). Game theoretic models for a closed-loop supply chain
with stochastic demand and backup supplier under dual channel recycling. https://doi.org/10.31181/dmame2003015g;
o Çam, Ömer N., & Sezen, H. K. (2020). The formulation of a linear programming model
for the vehicle routing problem in order to minimize idle time. https://doi.org/10.31181/dmame2003132h
We improve all the literature analysis, we add 12 papers of more recent period in
the first three paragraphs of the literature review “Considering uncertainty within
optimization problems remains a trending topic to be investigated because organizations
face to stochastic variables when making decisions. A search was carried out in Scopus
and in Web of Science written during 2020 and 2021 that used stochastic programming
to solve optimization problems. Huang et. al [5] develop a multistage stochastic optimization
model for system operators to efficiently schedule power-generation assets to co-optimize
power generation and regulation reserve service under uncertainty. Ghayour et al.
[6] present an approach called MLPR with linear programming used as its core in order
to solve the influence maximization problem in the linear threshold model, that is
one of two classic stochastic propagation models that describe the spread of influence
in a network. Robust Multi-product Newsvendor Model with Substitution, where the demand
and the substitution rates are stochastic and are subject to cardinality-constrained
uncertainty sets that is an NP hard problem is presented in [7].
Also, Basciftci et. al [8] reformulate the robust facility location problem, in which
they interpret the moments of stochastic demand as functions of facility-location
decisions. In Shone et. al [9], stochastic modeling applications within aviation are
presented, with a particular focus on problems involving demand and capacity management
and the mitigation of air traffic congestion; using operations research perspective,
including analytical queueing theory, stochastic optimal control, robust optimization
and stochastic integer programming. Ghasemi et. al [10] present an Evolutionary Learning
Based Simulation Optimization (ELBSO) method embedded within Ordinal Optimization.
In ELBSO a Machine Learning (ML) based simulation metamodel is created using Genetic
Programming (GP) to replace simulation experiments aimed at reducing computation;
ELBSO is evaluated on a Stochastic Job Shop Scheduling Problem (SJSSP). Zhang et.
al [11], consider a stochastic vehicle routing problem with probability constraints;
the probability that customers are served before their (uncertain) deadlines must
be higher than a pre-specified target. Wang et. al [12] propose a model to solve a
project scheduling problem where resource assignments and activity schedules need
to be determined to achieve a set of due-date requirements as well as possible. Torres
et. al [13] present multistage stochastic program for the design and management of
flexible infrastructure networks with stochastic demands.
In the methods for solving stochastic programming, Dowson and Kapelevich [14] develop
the Julia package for multistage stochastic and dual programming and Gangammanavar
et. al [15] work with stochastic decomposition for two-stage stochastic linear programs
with random cost coefficients.
Also we include a comparative table of the related works in Table 1 and an analysis
of this table in the last paragraph “Reviewing the works found that are related to
stochastic programming, it was observed that all of them use mixed integer programming,
Jamalnia et al. [16], Zhao et al. [18] and Tirkolaee et al. [22] with nonlinear multiobjective,
while Kazemi et al. [24] uses multistage stochastic programming which is the same
as that used in our proposal. Tirkolaee et al. [22] use demand and costs as stochastic
variables, while Kazemi et al. [24] demand and yield; the others, only use a single
variable as a stochastic. In their approaches, a single approximation is used to explain
the uncertainty, which is discrete, that is, a single stochastic model, and in our
case two models, that allow us to compare between the normal distribution and its
discretization in order to offer to the company a good solution in a reasonable computational
time. The proposals found use the scenerio tree, except Tirkolaee et al. [22] that
deal with the problem with weighted goal using GAMS. The level of service is only
handled in Zhao et al. [18], but the impact of the service level on the solution is
not considered. The sensitivity analysis varying stochastic parameters was not used
in the approaches found. After analyzing the characteristics of the studies found,
the gap was in considering the level of service, which was a very important restriction
for the company in the case study, considering demand and labor as stochastic variables,
which were two variables that generate a lot of uncertainty in the company and varying
the stochastic parameters. Finally, generate an efficient model, that is to say,
a model that obtains a good response in a reasonable computational time, for that
reason 2 models were tested for comparison.
-Add advantages and limitations of the proposed methodology and this study.
The advantages and limitations are in the second paragraph of the conclusions “The
advantages offered by the methodology proposed is its flexibility, being able to use
it in other problems where there is uncertainty. Some of its limitations, are the
need for goodness of fit tests that ensure that the data have a certain probability
distribution; if they are not done, the results will be far from optimal Also, the
sample size or number of possible realizations of a random variable when it is discretized
can make the problem difficult to solve, because the equivalent deterministic grow
exponentially as the number of states increases, for this study; solving a fifth
state would imply solving a deterministic equivalent of more than two million decision
variables and four million constraints because more than 40,000 scenarios are required,
which is the maximum number of scenarios that the Lingo software can process without
having a computational memory deficit.”
Reviewer #2: This work proposes two multi-stage stochastic linear programming models,
which are applied to an aggregate production plan (APP) for a furniture manufacturing
company located in the state of Hidalgo, Mexico. I have read the manuscript with great
interest and found that the idea is interesting but presentation style is poor. From
my point of view, its quality and novelty is not enough to be published in PLOS ONE
journal. I try to justify my opinion:
� Language of the paper must be improved as there are many mistakes and it is hard
to clearly understand the flow of the paper.
We review our article with a native American speaker and we correct the typographical
o and grammatical errors
� Objectives of this work are not convincing.
We modified the objectives of this work in the second paragraph of the introduction
“The main objective of this article is to develop a multi-state stochastic optimization
model applied to an APP of a local company, where the production periods are defined
as the states, the randomness of production capacity and demand are modeled through
a continuous probability distribution using the stochastic programming solver integrated
by Lingo. Two models are proposed, Model-I only could solve the problem for a maximum
of three periods, due the complexity of using a continuous probability distribution
, a second model is proposed with a discretization of the probability distributions
(Model-II) which could solve the problem up to four periods. In both models a scenario
tree is created. In general, this work compares the efficiency between Model-I and
Model-II in resolution time, number of iterations, expected value (EV), wait-and-see
value (WS), and expected value of perfect information (EVPI). The obtained results
help to determine the advantages about the proposed model (Model-II) with respect
to Model I and is useful to understand the scope of both models and in which cases
it is advisable to use each one. In addition, both models consider the impact of the
service level restriction on the optimal solution and what happen when parameters
of the distribution probabilities are varying”
� The novelty of this work is not clear.
The novelty of this work could be summarized in five points and are in the third and
fourth paragraph of the introduction “1) this study provides a mathematical programming
model that has been adapted for real needs of a company, which incorporates a service
level constraint that it is not found in the literature, usually a confidence percentage
is used (which could turn the problem into a chance constraint programming. 2) In
the literature only the expected value of the objective function is reported (here
and now solution) with the history of the process considered, that is, with the nonanticipativity
constraints or the value of the expected objective function. If these constraints
are removed, the wait and see solution appears, in our research, both solutions are
reported, also the absolute difference of the two solutions is reported, called the
expected value of perfect information that could help the company to deal with uncertainty
in economic decisions. 3) An extensive sensitivity analysis is carried out, varying
the cost parameters, the percentage of the service level and varying the parameters
of the probability distribution of uncertainty. Few studies carry out a sensitivity
analysis, but in our knowledge, nobody analyzes the impact of service level and varies
the parameters of the probability distribution. Through this sensitivity analysis,
interesting results were obtained, for example, that the total cost of the APP goes
down, when the variability of the production capacity (standard deviation of the probability
distribution) is reduced. 4) Due to the complexity of the problem, the software could
not solve the problem satisfactorily for a fourth period, finding a solution that
is only feasible, then, a second model is developed using discretization of the probability
distribution, it has been shown that if the distances of both distributions are minimal,
the solution found is closer than the true optimum [2-4] the quality of the proposed
model is presented in the results, where both models are compared.
Finally, 5) a methodology to deal with problems using stochastic programming is proposed,
although it was applied to the case of this APP, can be implemented in other areas
of industrial engineering sciences, such as supply chain networks, problems of vehicle
routing, design, and redesign of layouts, among others. Advantages and disadvantages
are detailed in the conclusions section. Table 1 shows a comparison between some relevant
studies in the area and our study, so that the novelty and contribution of our proposal
can be observed”
� Abstract and Introduction section have poorly written. Introduction section should
be updated with motivation behind this study, research gap, novelty and contributions
of the work.
The abstract was modified writing the novelty of our work in the last sentence “In
this article two multi-stage stochastic linear programming models are developed, one
applying the stochastic programming solver integrated by Lingo 17.0 optimization software
that utilizes an approximation using an identical conditional sampling and Latin-hyper-square
techniques to reduce the sample variance, associating the probability distributions
to normal distributions with defined mean and standard deviation; and a second proposed
model with a discrete distribution with 3 values and their respective probabilities
of occurrence. In both cases, a scenario tree is generated. The models developed are
applied to an aggregate production plan (APP) for a furniture manufacturing company
located in the state of Hidalgo, Mexico, which has important clients throughout the
country. Production capacity and demand are defined as random variables of the model.
The main purpose of this research is to determine a feasible solution to the aggregate
production plan in a reasonable computational time. The developed models were compared
and analyzed. Moreover, this work was complemented with a sensitivity analysis; varying
the percentage of service level, also, varying the stochastic parameters (mean and
standard deviation) to test how these variations impact in the solution and decision
variables”.
The introduction section was updated with research gag, novelty and contributions
of the work “Therefore, the motivation for this work is to improve productivity, have
efficient policies to manage its production and minimize production costs, developing
models of aggregate production plans (APP) with uncertainty due to a real need of
a furniture company, Models are considering real characteristics such as human factor,
multi-period production criteria and service level policy due to the use of backlogs.
The main objective of this article is to develop a multi-state stochastic optimization
model applied to an APP of a local company, where the production periods are defined
as the states, the randomness of production capacity and demand are modeled through
a continuous probability distribution using the stochastic programming solver integrated
by Lingo. Two models are proposed, Model-I only could solve the problem for a maximum
of three periods, due the complexity of using a continuous probability distribution
, a second model is proposed with a discretization of the probability distributions
(Model-II) which could solve the problem up to four periods. In both models a scenario
tree is created. In general, this work compares the efficiency between Model-I and
Model-II in resolution time, number of iterations, expected value (EV), wait-and-see
value (WS), and expected value of perfect information (EVPI). The obtained results
help to determine the advantages about the proposed model (Model-II) with respect
to Model I and is useful to understand the scope of both models and in which cases
it is advisable to use each one. In addition, both models consider the impact of the
service level restriction on the optimal solution and what happen when parameters
of the distribution probabilities are varying.
The novelty of this work could be summarized in five points,1) this study provides
a mathematical programming model that has been adapted for real needs of a company,
which incorporates a service level constraint that it is not found in the literature,
usually a confidence percentage is used (which could turn the problem into a chance
constraint programming. 2) In the literature only the expected value of the objective
function is reported (here and now solution) with the history of the process considered,
that is, with the nonanticipativity constraints or the value of the expected objective
function. If these constraints are removed, the wait and see solution appears, in
our research, both solutions are reported, also the absolute difference of the two
solutions is reported, called the expected value of perfect information that could
help the company to deal with uncertainty in economic decisions. 3) An extensive sensitivity
analysis is carried out, varying the cost parameters, the percentage of the service
level and varying the parameters of the probability distribution of uncertainty. Few
studies carry out a sensitivity analysis, but in our knowledge, nobody analyzes the
impact of service level and varies the parameters of the probability distribution.
Through this sensitivity analysis, interesting results were obtained, for example,
that the total cost of the APP goes down, when the variability of the production capacity
(standard deviation of the probability distribution) is reduced. 4) Due to the complexity
of the problem, the software could not solve the problem satisfactorily for a fourth
period, finding a solution that is only feasible, then, a second model is developed
using discretization of the probability distribution, it has been shown that if the
distances of both distributions are minimal, the solution found is closer than the
true optimum [2-4] the quality of the proposed model is presented in the results,
where both models are compared.
Finally, 5) a methodology to deal with problems using stochastic programming is proposed,
although it was applied to the case of this APP, can be implemented in other areas
of industrial engineering sciences, such as supply chain networks, problems of vehicle
routing, design, and redesign of layouts, among others. Advantages and disadvantages
are detailed in the conclusions section. Table 1 shows a comparison between some relevant
studies in the area and our study, so that the novelty and contribution of our proposal
can be observed.
The contribution of this work is a real problem where uncertainty affects the production
system, generally, the models used in the literature consider demand as a random variable
with a discrete approximation (one model), in this work, in addition, the human factor
is considered as a stochastic parameter that can be modeled and 2 models are compared”.
� Literature review is just providing summary of existing works without any insightful
conclusions.
We include a comparative table of the related works in Table 1 and an analysis of
this table in the last paragraph “Reviewing the works found that are related to stochastic
programming, it was observed that all of them use mixed integer programming, Jamalnia
et al. [16], Zhao et al. [18] and Tirkolaee et al. [22] with nonlinear multiobjective,
while Kazemi et al. [24] uses multistage stochastic programming which is the same
as that used in our proposal. Tirkolaee et al. [22] use demand and costs as stochastic
variables, while Kazemi et al. [24] demand and yield; the others, only use a single
variable as a stochastic. In their approaches, a single approximation is used to explain
the uncertainty, which is discrete, that is, a single stochastic model, and in our
case two models, that allow us to compare between the normal distribution and its
discretization in order to offer to the company a good solution in a reasonable computational
time. The proposals found use the scenerio tree, except Tirkolaee et al. [22] that
deal with the problem with weighted goal using GAMS. The level of service is only
handled in Zhao et al. [18], but the impact of the service level on the solution is
not considered. The sensitivity analysis varying stochastic parameters was not used
in the approaches found. After analyzing the characteristics of the studies found,
the gap was in considering the level of service, which was a very important restriction
for the company in the case study, considering demand and labor as stochastic variables,
which were two variables that generate a lot of uncertainty in the company and varying
the stochastic parameters. Finally, generate an efficient model, that is to say,
a model that obtains a good response in a reasonable computational time, for that
reason 2 models were tested for comparison”.
� The structure of the whole paper should be improved.
We structure the paper as Plos One guidelines suggest: (Abstract, Introduction, Materials
and methods , Results, Discussion, Conclusions.). In our paper, Material and Methods
are the Methodology, the sections are consistent with the steps of figure 2.
� Why someone should use your proposed work in practice, and what are the advantages
of your work in comparison with others.
The gap founded in the literature that is included in our research is in the last
paragraph of the literature review, “The level of service is only handled in Zhao
et al. [18], but the impact of the service level on the solution is not considered.
The sensitivity analysis varying stochastic parameters was not used in the approaches
found. After analyzing the characteristics of the studies found, the gap was in considering
the level of service, which was a very important restriction for the company in the
case study, considering demand and labor as stochastic variables, which were two variables
that generate a lot of uncertainty in the company also varying the stochastic parameters.
Finally, generate an efficient model, that is to say, a model that obtains a good
response in a reasonable computational time, for that reason 2 models were tested
for comparison”. These are advantages of our work, we present a sensitivity analysis
of the service level (in percentage), also we include this sensitivity analysis in
the stochastic parameters in order to present the enterprise how robust are both models
to find a solution in a reasonable computational time. Other industries could use
our methodology and also could consider that both models have similar solutions and
the discretization of the distributions works more efficient than use the normal distribution.
� Summarise the advantages and limitations of the proposed method in practical applications.
The advantages and limitations are in the second paragraph of the conclusions “The
advantages offered by the methodology proposed is its flexibility, being able to use
it in other problems where there is uncertainty. Some of its limitations, are the
need for goodness of fit tests that ensure that the data have a certain probability
distribution; if they are not done, the results will be far from optimal Also, the
sample size or number of possible realizations of a random variable when it is discretized
can make the problem difficult to solve, because the equivalent deterministic grow
exponentially as the number of states increases, for this study; solving a fifth
state would imply solving a deterministic equivalent of more than two million decision
variables and four million constraints because more than 40,000 scenarios are required,
which is the maximum number of scenarios that the Lingo software can process without
having a computational memory deficit.”
� Comparison with existing studies should be added.
We improve all the literature analysis, we add 12 papers of more recent period in
the first three paragraphs of the literature review “Considering uncertainty within
optimization problems remains a trending topic to be investigated because organizations
face to stochastic variables when making decisions. A search was carried out in Scopus
and in Web of Science written during 2020 and 2021 that used stochastic programming
to solve optimization problems. Huang et. al [5] develop a multistage stochastic optimization
model for system operators to efficiently schedule power-generation assets to co-optimize
power generation and regulation reserve service under uncertainty. Ghayour et al.
[6] present an approach called MLPR with linear programming used as its core in order
to solve the influence maximization problem in the linear threshold model, that is
one of two classic stochastic propagation models that describe the spread of influence
in a network. Robust Multi-product Newsvendor Model with Substitution, where the demand
and the substitution rates are stochastic and are subject to cardinality-constrained
uncertainty sets that is an NP hard problem is presented in [7].
Also, Basciftci et. al [8] reformulate the robust facility location problem, in which
they interpret the moments of stochastic demand as functions of facility-location
decisions. In Shone et. al [9], stochastic modeling applications within aviation are
presented, with a particular focus on problems involving demand and capacity management
and the mitigation of air traffic congestion; using operations research perspective,
including analytical queueing theory, stochastic optimal control, robust optimization
and stochastic integer programming. Ghasemi et. al [10] present an Evolutionary Learning
Based Simulation Optimization (ELBSO) method embedded within Ordinal Optimization.
In ELBSO a Machine Learning (ML) based simulation metamodel is created using Genetic
Programming (GP) to replace simulation experiments aimed at reducing computation;
ELBSO is evaluated on a Stochastic Job Shop Scheduling Problem (SJSSP). Zhang et.
al [11], consider a stochastic vehicle routing problem with probability constraints;
the probability that customers are served before their (uncertain) deadlines must
be higher than a pre-specified target. Wang et. al [12] propose a model to solve a
project scheduling problem where resource assignments and activity schedules need
to be determined to achieve a set of due-date requirements as well as possible. Torres
et. al [13] present multistage stochastic program for the design and management of
flexible infrastructure networks with stochastic demands.
In the methods for solving stochastic programming, Dowson and Kapelevich [14] develop
the Julia package for multistage stochastic and dual programming and Gangammanavar
et. al [15] work with stochastic decomposition for two-stage stochastic linear programs
with random cost coefficients.
Also we include a comparative table of the related works in Table 1 and an analysis
of this table in the last paragraph “Reviewing the works found that are related to
stochastic programming, it was observed that all of them use mixed integer programming,
Jamalnia et al. [16], Zhao et al. [18] and Tirkolaee et al. [22] with nonlinear multiobjective,
while Kazemi et al. [24] uses multistage stochastic programming which is the same
as that used in our proposal. Tirkolaee et al. [22] use demand and costs as stochastic
variables, while Kazemi et al. [24] demand and yield; the others, only use a single
variable as a stochastic. In their approaches, a single approximation is used to explain
the uncertainty, which is discrete, that is, a single stochastic model, and in our
case two models, that allow us to compare between the normal distribution and its
discretization in order to offer to the company a good solution in a reasonable computational
time. The proposals found use the scenerio tree, except Tirkolaee et al. [22] that
deal with the problem with weighted goal using GAMS. The level of service is only
handled in Zhao et al. [18], but the impact of the service level on the solution is
not considered. The sensitivity analysis varying stochastic parameters was not used
in the approaches found. After analyzing the characteristics of the studies found,
the gap was in considering the level of service, which was a very important restriction
for the company in the case study, considering demand and labor as stochastic variables,
which were two variables that generate a lot of uncertainty in the company and varying
the stochastic parameters. Finally, generate an efficient model, that is to say,
a model that obtains a good response in a reasonable computational time, for that
reason 2 models were tested for comparison”.
� Conclusions section has poorly written. Conclusion section should be rewritten by
adding advantages, limitations and useful future research directions of the proposed
work.
We rewrite the conclusions considering advantages, limitations and future research
directions, There are in the second, third fourth paragraphs of the conclusions “The
advantages offered by the methodology proposed is its flexibility, being able to use
it in other problems where there is uncertainty. Some of its limitations, are the
need for goodness of fit tests that ensure that the data have a certain probability
distribution; if they are not done, the results will be far from optimal Also, the
sample size or number of possible realizations of a random variable when it is discretized
can make the problem difficult to solve, because the equivalent deterministic grow
exponentially as the number of states increases, for this study; solving a fifth
state would imply solving a deterministic equivalent of more than two million decision
variables and four million constraints because more than 40,000 scenarios are required,
which is the maximum number of scenarios that the Lingo software can process without
having a computational memory deficit.
The study was complemented with sensitivity analysis, in the literature few studies
report these analyzes, generally only perform it by varying parameters associated
with costs, but in this study is carried out to see the impact of varying the percentage
of the policy of level of service, a sensitivity analysis is also carried out, seeing
how by varying the parameters of the probability distributions or stochastic parameters
(mean and standard deviation) impacts in the solutions and decision variables, so
that the company has sufficient information for correct planning in case these parameters
could change in the future, or, as an area of opportunity to improve productivity,
for example, it could be observed that reducing the variability of the random variable
production capacity, that is, reducing its standard deviation, reduces the total cost
of the APP.
Since many of the APPs occupy neither linear functions, a direction for future research
is to make a model considering some non-linear functions, such as the inventory cost,
also reformulate the problem, removing some restrictions that will allow to have a
lower inventory level, allowing to solve the problem in a more efficient way, it is
also interested in the use of another algorithm to solve the equivalent determinists,
in this work the algorithm B-and-B was used, being able also to use algorithms of
cut of plan, consider using multiple kernels in parallel, using multiple heuristics
to pre-solve the problem, and using robust algorithms for relaxation of the problem”
� References are not consistent.
We made consistent the references using the guidelines of Plos One published in https://journals.plos.org/plosone/s/submission-guidelines#loc-references
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Reviewer #1: No
Reviewer #2: No
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Thank you for your time,
Best regards,
Eva
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