52 ISE Magazine | www.iise.org/ISEmagazine
Inside IISE Journals
research
How tailored clustering approaches reduce
the spread of infectious disease outbreaks
Cluster analysis is one of the most adopted unsupervised
learning methods with uses that arise in various applica-
tions, some with a significant impact on human lives. While
several off-the-shelf clustering techniques exist, many of
these techniques perform poorly for specific problem types.
This is largely attributed to three factors: First, existing ap-
proaches are based on approximate schemes with no guar-
antees. Consequently, the resulting recommendations can
deviate, sometimes substantially, from global optimality.
Second, there is no clear way of selecting between existing
approaches, leaving practitioners in the dark as to which
technique to adopt. Third, these techniques do not account
for specific problem structure which, if taken advantage of,
can improve solution performance.
In their work, “Optimal Clustering of Frequency Data
with Application to Disease Risk Categorization,” Texas
A&M University assistant professor Hrayer Aprahamian
and George Mason University assistant professor Hadi El-
Amine investigate novel clustering procedures that are tai-
lored to handle a specific type of data, frequency data, that
commonly arises in numerous applications. The tailored
approach provides many advantages over conventional
procedures by exploiting the structure of the problem. Al-
though the work is specific to frequency data, their results
are independent of the application, which greatly broadens
its usability.
The authors achieve this by interpreting the process
of clustering a dataset as a procedure that characterizes a
unique discrete distribution. This novel interpretation al-
lows them to extract valuable statistical information, which
they embed within an optimization framework. To solve
the resulting challenging combinatorial optimization prob-
lem, the authors construct a scheme that casts the clustering
problem as a tractable network problem. This reformulation
scheme enables the construction of an efficient polynomial-
time algorithm that guarantees global optimality.
The authors demonstrate the use of the developed meth-
odologies through an application that aims to identify
screening strategies that mitigate the spread of infectious
diseases. In this context, the population needs to be clus-
tered into risk categories in a manner that maximally high-
lights their heterogeneity. Doing so provides practitioners a
tool that not only identies optimal categories, but one that
enables the construction of custom screening approaches.
Their results reveal that the considered approach con-
This month we highlight two articles in IISE Transactions. The first article focuses on how to tailor clustering of
heterogenous data and how that practice helps reduce the spread of infectious disease outbreaks. The authors investigated
a novel clustering procedure for handling frequency data, which is to interpret the process of clustering that characterizes
a unique discrete distribution. This reformulation enables the construction of an efcient polynomial-time algorithm that
guarantees global optimality, and the tailored clustering significantly reduces misclassifications when applied to identifying
screening strategies that mitigate the spread of infectious diseases. The second article attempts to provide an understanding
of the possible effects of competition in terms of consumption and economic welfare for providing water services.
The authors studied two types of competition – one based on an attraction model for water providers within a public-
private partnership and another involving quantity competition within a spot market. The authors found that spot-market
competition does not necessarily result in greater levels of supply, nor in a lower price, and that a public-private partnership
could be preferable. These articles will appear in the August 2022 issue of IISE Transactions (Volume 54, No. 8).
.
Hrayer Aprahamian Hadi El-Amine
July 2022 | ISE Magazine 53
sistently outperforms current practices by signicantly re-
ducing misclassification while using the same amount of
resources. Such results underscore the value of tailored
optimization-based approaches in addressing complex real-
world challenges.
CONTACT: Hrayer Aprahamian; hrayer@tamu.edu; Wm Michael Barnes
64 Department of Industrial and Systems Engineering, Texas A&M
University, College Station, TX 77840; Hadi El-Amine; helamine@gmu.
edu; Systems Engineering and Operations Research Department, George
Mason University, Fairfax, VA 22030
Using a dynamic model to decide if
public-private partnership is preferable to
spot market competition for water services
Water consumption is increasing due to worldwide popula-
tion growth, the urbanization of countries around the globe
and the demand for a higher quality of life. Actually, wa-
ter joined gold, oil and other commodities traded on Wall
Street, highlighting worries that the life-sustaining natural
resource may become scarce across most of the world.
In many countries, policymakers face the dilemma of
how to respond to increasing physical water scarcity. There-
fore, considerable effort has been expended in improving
the productive efficiency of the water sector using a variety
of methods, including concentration, competition for the
market, competition in the market and cooperation. Thus
far, however, these strategies have only been implemented
in a limited way and the consequences of introducing them
remain unclear.
In their work, “Water scarcity and welfare: Regulated
Public-Private Supply Chain Versus Spot-Market Compe-
tition,” chaired professor Konstantin Kogan, postdoctoral
student Dmitry Tsadikovich and associate professor Tal
Avinadav, all from Bar-Ilan University in Israel, attempt
to understand the possible effects of competition in terms
of consumption and economic welfare. They contrast the
standard monopolistic approach to supplying water with
two different types of competition. One type is based on an
attraction model for water providers within a public-private
partnership, while the second type involves quantity com-
petition within a spot market.
Unlike the case of quan-
tity competition, which im-
plies dynamic pricing, the
public-private supply chain
is characterized by a state-
regulated price that is fixed
over the period of the con-
tract and that is set at a level
to just recover the associated
distribution costs of the pub-
lic entity.
The authors derive dynamic equilibrium replenishment
and inventory policies to show that, contrary to expecta-
tions, spot-market competition does not necessarily result
in greater levels of supply, nor in a lower price, than does
a regulated supply chain. In particular, if the distribution
cost is relatively low, then by encouraging a public-private
partnership, the public entity (municipality or state utility
company) can ensure higher consumer surplus compared to
a spot market.
On the other hand, increasing the distribution cost and
hence the regulated price is likely to diminish the differ-
ences between the two market types. In such a case, man-
aging water supplies for the municipality by means of a spot
market would become advantageous. Specifically, it would
help the public entity to manage the risk of shortages and
better align supply and demand.
CONTACT: Konstantin Kogan; Konstantin.kogan@biu.ac.il; Bar-Ilan
University, Faculty of Social Sciences, Department of Management, Max
ve-Anna Webb Street, Ramat-Gan, ISRAEL 5290002
This month we highlight two articles from IISE
Transactions on Healthcare Systems Engineering
(Volume 12, No. 2). The first article measures
the total patient value received from creating
a mix of cases for surgeons of varying levels
of experience. The goal is to maintain a high
level of patient outcomes but counterbalance
caseloads to allow less experienced surgeons to
improve their skills. The second article gathers
information from surveys with patients and
caregivers to aid in the design of a wearable
dialysis device. Such a device could provide
increased quality of life for patients suffering
from renal disease if user-centered design
principles are applied to take patients’ needs
and perspectives into account throughout the
product development process.
Konstantin Kogan
Dmitry Tsadikovich Tal Avinadav
54 ISE Magazine | www.iise.org/ISEmagazine
research
How surgical units can leverage
the diversity in surgeons’ experience
levels to improve patient outcomes
While the observance of hos-
pital treatment guidelines and
protocols is critical for good
medical outcomes that di-
rectly offer value to patients, a
surgeons case mix could also
be a critical factor impacting
patient outcomes. When dif-
ficult cases are mostly seen
by experienced surgeons, less
experienced surgeons miss
the opportunity to improve
their skills. However, when
less experienced surgeons see
too many difficult cases, it could produce poor patient out-
comes.
Renato de Matta of the University of Iowa College of
Business examines this trade-off in his paper, “Patient-
Centric Surgeons Case Mix Problem.” He shows how the
diversity in experience level of surgeons complements a sur-
gical unit in a way in which good patient outcomes from
experienced surgeons counterbalance the average but im-
proving patient outcomes from less experienced surgeons,
while less experienced surgeons gain more experience.
He formulates and solves an optimization model that
nds the case mix of surgeons in a surgical unit that maxi-
mizes the units total patient value (TPV) per dollar expen-
diture on healthcare resources. Numerical experiments us-
ing laparoscopic colectomy data show workload balancing
and patient self-selection of surgeon could reduce total pa-
tient value; if the number of patients seen by each surgeon is
restricted, achieving excellent outcomes for high value sur-
geries by managing the learning that takes place improves
TPV; a balanced mix of easy and hard cases produces higher
TPV; and high demand uncertainty increases the mismatch
between the value surgeons can deliver to patients and the
value demanded by patients which lowers TPV.
Examples of practical applications of the model are: Plan-
ning the mix of patients seen by junior surgeons in residen-
cy programs at teaching hospitals; U.S. hospitals that accept
diagnosis-related groups (DRG) based on reimbursements
could plan their budget using TPV. An actual TPV that is
higher than projected is an indication of good patient out-
comes, which could result in cost savings and produce good
nancial performance for hospitals.
CONTACT: Renato de Matta, Ph.D.; renato-dematta@uiowa.edu; Busi-
ness Analytics and Information Systems Department, 108 Pappajohn
Business Building, University of Iowa College of Business, Iowa City IA
52242-1994
Realizing the dream of a wearable
dialysis device: What do patients
and their care partners want?
Imagine that your schedule is structured around visiting a
dialysis center two or three times a week for the rest of your
life. Each visit requires you to spend four to six hours at
the center connected to a stationary dialysis machine that
cleans your blood.
This is the reality for most patients with end-stage re-
nal disease (ESRD), the condition of irreversible kidney
failure.
The in-center mode of dialysis therapy negatively im-
pacts ESRD patients’ quality of life such as impairing their
mobility, independence and mental health. Because of these
challenges and other difculties resulting from the disease,
many ESRD patients need the support of a care partner to
assists with their healthcare needs and daily activities.
The Center for Dialysis Innovation (CDI) at the Univer-
sity of Washington (UW) is developing a wearable dialysis
device to transform current dialysis therapies by allowing
ESRD patients to undergo continuous dialysis wherever
they are.
To design a wearable dialysis device patients are willing
to use, it is important that researchers apply user-centered
design principles. The user-centered design takes users
needs and perspectives into account throughout the prod-
Renato de Matta of the
University of Iowa College
of Business.
Auður Anna Jónsdóttir Larry G. Kessler
Seung-Yeon Rim Ji-Eun Kim
July 2022 | ISE Magazine 55
IIISE Transactions (link.iise.org/iisetransactions) is IISE’s flagship
research journal and is published monthly. It aims to foster
exchange among researchers and practitioners in the industrial
engineering community by publishing papers that are grounded
in science and mathematics and motivated by engineering
applications.
IISE Transactions on Healthcare Systems Engineering (link.iise.org/
iisetransactions_healthcare) is a quarterly, refereed journal that
publishes papers about the application of industrial engineering tools
and techniques to healthcare systems.
To subscribe, call (800) 494-0460 or (770) 449-0460.
About the journals
uct development process.
In “What Patients and Care Partners Want in Designing
a Wearable Dialysis Device: A Mixed-Methods Study,” the
human factors team at the CDI joins forces with Auður
Anna Jónsdóttir, a doctoral student in industrial and sys-
tems engineering at UW; Larry G. Kessler, a professor in
the department of health systems and population health at
UW; Seung-Yeon Rim, a UW industrial and systems engi-
neering graduate; and Ji-Eun Kim, an ISE assistant profes-
sor at UW.
By interviewing 24 ESRD patients and 12 care partners,
the interdisciplinary team of researchers identified similari-
ties and differences in ESRD patients’ and care partners’
preferences for the designs of a wearable dialysis device.
The findings from this study can help guide researchers
in designing a patient- and care partner-centered wearable
dialysis device.
CONTACT: Ji-Eun Kim, jikim@uw.edu; Industrial & Systems Engineering,
University of Washington, Box 352650, Seattle, WA 98195
Yu Ding is the Mike and Sugar Barnes Professor of Industrial
and Systems Engineering at Texas A&M University and Associ-
ate Director for Research Engagement at the Texas A&M Institute
of Data Science. He is editor-in-chief of IISE Transactions and
a fellow of IISE.
Oguzhan Alagoz is a professor in the Department of Industrial and
Systems Engineering at the University of Wisconsin-Madison. He
is editor-in-chief of IISE Transactions on Healthcare Systems
Engineering and a fellow of IISE.
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