A Task-oriented Requirements Engineering Method for
Personal Decision Support Systems
A Case Study
Christian Kücherer and Barbara Paech
Institute for Computer Science, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
Keywords:
Decision Support System, DSS, Personal DSS, Requirements Specification, Task-oriented Requirements
Engineering, TORE.
Abstract:
[Context and motivation] Personal Decision Support Systems (PDSSs) are information systems which sup-
port executives in decision-making by a decision- and user-specific data presentation. PDSSs operate on
current data with predefined queries and provide a rich user interface (UI). Thus, a Requirements Engineering
(RE) method for PDSSs should support the elicitation and specification of detailed requirements for specific
decisions. However, existing RE approaches for decision support systems typically focus on ad-hoc decisions
in the area of data warehouses. [Question/problem] Task-oriented RE (TORE) emphasizes a comprehen-
sive RE specification which covers stakeholders’ tasks, data, system functions, interactions, and UI. TORE
allows an early UI prototyping which is crucial for PDSS. Therefore, we want to explore TORE’s suitability
for PDSSs. [Principal ideas/results] According to the Design Science methodology, we assess TORE for
its suitability of PDSS specification in a problem investigation. We propose decision-specific adjustments of
TORE (DsTORE), which we evaluate in a case study. [Contribution] The contribution of this paper is three-
fold. First, the suitability of the task-oriented RE method TORE for the specification of a PDSS is investigated
as problem investigation. Second, a decision-specific extension of TORE is proposed as the DsTORE-method
in order to identify and specify details of decisions to be supported by a PDSS. DsTORE is evaluated in a case
study. Third, experiences from the study and method design are presented.
1 INTRODUCTION
Today, data warehouses (DW) are standard technol-
ogy for decision support in companies. They are a
specific form of Decision Support Systems (DSSs)
which represents a subgroup of information systems.
As discussed in a recent overview by Hosack et
al. (Hosack et al., 2012), there is a large variety of
DSSs and an extensive history of research on DSSs.
At the same time, this research is ongoing and incor-
porates new trends such as social media or mobile
computing (Gao, 2013). Similarly, there is a grow-
ing field of research focusing on the development
methodologies for DSS. Saxena (Saxena, 1991) is a
very early development methodology which empha-
sizes the understanding of decision tasks and proto-
typing. In a more recent review Gachet and Haetten-
schwiler investigate early and widely acknowledged
development processes of DSSs (Gachet and Haetten-
schwiler, 2006), focusing on either decisions or sys-
tem engineering or both. They also emphasize the im-
portance of an evolutionary approach which pays at-
tention to both, organizational and technical issues. In
the same vein Arnott (Arnott, 2010) develops a busi-
ness intelligence development approach starting from
a fundamental understanding of senior executives’ be-
havior. We are interested in Personal DSSs (PDSSs,
introduced in detail in Section 2.2) which are small-
scale systems that support decision-making of one or
a small group of executives with an exactly defined
set of supported decisions (Arnott, 2008). While the
early approaches to DSS provide a general frame-
work, they do not describe a detailed requirements
engineering method. Whilst retaining the empha-
sis of these methodologies, we take the task-oriented
RE approach TORE (Paech and Kohler, 2004; Adam
et al., 2009) as our basis to develop a detailed re-
quirements engineering method for PDSSs. TORE
has proven useful for information systems and it sup-
ports a refinement of requirements concerning all sys-
tem details up to the UI, and thus to early prototyping.
However, it has not yet been applied to PDSSs.
Kücherer, C. and Paech, B.
A Task-oriented Requirements Engineering Method for Personal Decision Support Systems - A Case Study.
DOI: 10.5220/0006325300990110
In Proceedings of the 19th International Conference on Enterprise Information Systems (ICEIS 2017) - Volume 2, pages 99-110
ISBN: 978-989-758-248-6
Copyright © 2017 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
99
Table 1: Operational and decisional systems. (Left three columns acc. (García et al., 2016) and (Salinesi and Gam, 2009),
except rows structure of data and predefined decisions).
Operational Decisional PDSS
Objective busin. operation busin. analysis specific busin. decisions
Main functions daily operations (OLTP) DSS (OLAP) decision-specific UI data presen-
tation, reporting
Decisions n/a un-,semi-,structured semi-, structured
Usage repetitive, predef. innovative, unexp. repetitive, predef.
Design orientation functionality subject subject
Kind of users clerk executives executives
Number of users thousands hundreds one to ten
Accessed tuples hundreds thousands hundreds
Data sources (dsrc) isolated integrated heterogeneous, isolated
Structure of dsrc structured structured un- and structured
Granularity atomic summarized atomic and summarized
Time coverage current historical current and historical
Access(work units) simple transact. complex queries simple queries
Size MB/GB GB/TB/Petabytes MB
With this recent scholarly background in mind,
the overall Research Question (RQ) of this paper is:
How can TORE be extended to support the RE of a
PDSS?. We follow the design science cycle described
by Wieringa (Wieringa, 2014) to answer this RQ. In
the problem investigation, we evaluate TORE’s suit-
ability to support the RE for PDSSs. In the treatment
design, we propose a decision-specific adaptation of
TORE (DsTORE). Finally, in the treatment validation
we evaluate DsTORE.
This paper is structured as follows. Section 2 in-
troduces PDSSs, presents the case for this study, and
offers a brief overview of TORE. Section 3 discusses
related work on RE for DSSs. The investigation of
TORE’s support for the RE of PDSSs is presented as
problem investigation in Section 4. The treatment de-
sign DsTORE is presented in Section 5. The treat-
ment validation is described in the form of a case
study in Section 6. The results of the problem in-
vestigation and case study are discussed in Section 7,
in which we also present the lessons that we have
learned. The threats to validity are discussed in Sec-
tion 8. Finally, the paper is concluded in Section 9 by
sketching some ideas of future work.
2 BACKGROUND
This section presents a brief introduction of PDSSs
and task-oriented RE as well as the case for our case
study.
2.1 Decisions and Decision Knowledge
A decision can be defined as a choice that is made
between multiple alternative courses of actions, and
that in turn leads to a desired objective (Holsapple,
2008a). Alternatives have implications and decision-
making requires knowledge. For example, the prior-
itization of projects (choice) results in a precedence
of one project over others (alternatives) based on a
project’s importance, benefit for operations, or the
estimated budget (knowledge). Structured decision
problems have defined criteria in order to make the
decision, known alternatives and implications, and re-
quire specific types of knowledge. By contrast, un-
structured decision problems are by their nature un-
expected, have unstable context and unknown alter-
natives, possess unknown criteria, and rely on situa-
tions in which none or an incomplete level of knowl-
edge is available (Holsapple, 2008a). Semi-structured
decision problems are in between. Decision knowl-
edge is taken from a data source, persisting data for
future access via interfaces or file access. Examples
of data sources are databases or documents such as
spreadsheets and text documents. A data source is de-
scribed through data source format, location, and con-
tent. For example a project list used by an executive
can be described using a spreadsheet (format), a URL
(location), and a list of projects (content). This is in
contrast with unstructured data, in which structured
data follows a formal definition of data types. Thus,
data sources of structured data are typically databases,
while semi-structured data is held in spreadsheets,
and unstructured data in text-documents.
2.2 Personal Decision Support Systems
In general DSSs support all kinds of decisions. Sali-
nesi et al. (Salinesi and Gam, 2009) provide a com-
parison of operational information systems (IS) and
DW (called decisional IS) which is adapted in (Gar-
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100
Goal & Task
Level (GT)
Domain
Level (D)
Interaction
Level (I)
System
Level (S)
Stakeholders
Tasks
As-is Activities To-be Activities
System
Respons.
Domain Data
System
Functions
Interaction
Interaction
Data
UI Structure
GUI
Application Core
Navigation/
Sup. Functions
Dialog UI-data
Screen
Structure
Internal
Actions
Internal
Data
Architecture
Supported
Stakeholders
Stakeholders
Goals
Data Sources
To-be Decision
Specific Subtasks
Categorization of
Subtasks
Legend:
DsTORE DP
DsTORE refined or
extended TORE DP
TORE DP
Figure 1: Decision Points of the TORE Framework (Paech and Kohler, 2004) and PDSS-specific extensions.
cía et al., 2016). DSSs in general cover a broad range
of different system types and incorporate a variety
of different techniques such as decision models or
artificial intelligence (Holsapple, 2008b; Arnott and
Pervan, 2005). The specifics of Personal DSSs have
been described by Arnott (Arnott, 2008). He sum-
marizes that PDSSs are developed for one or a small
group of managers with the goal to improve the pro-
cess and outcome of decision-making. The scope of a
PDSS is the support of one or a small number of deci-
sion tasks, where often semi-structured data based on
spreadsheets are used. The fact that PDSSs are small-
scale systems refers to the supported small number
of users and features and requirements. To delineate
PDSSs from DSSs in general, we add a third column
to Table 1. The objective of PDSSs is to support
decision-making within a defined context. Its main
function is to provide specific and predefined informa-
tion for structured and semi-structured decisions in an
overview UI or as a report to executives. In a similar
way to DW, the primary users are executives, who ac-
cess heterogeneous and isolated data sources at run-
time. In contrast to DW, usage is repetitive and pre-
defined and the amount of accessed data is not exten-
sive. Altogether, the data and data sources of PDSSs
are quite complex, while their usage is rather simple.
2.3 Task-oriented Requirements
Engineering
Task-orientation focuses on the RE process and helps
to deliver software that satisfies user needs (Paech and
Kohler, 2004). As a conceptual framework, TORE
provides a conceptual model for RE and has been
successfully applied in a number of IS development
projects of different problem domains (Adam et al.,
2009). Important aspects of the requirements speci-
fication are determined in each of TORE’s 18 Deci-
sion Points (DPs), which are grouped into four levels
of abstraction, as shown on the left part of Figure 1.
Note that TORE’s DPs are distinct from decisions in
the context of DSSs. The goal & task level focuses on
stakeholders, goals, and tasks. Tasks are often activi-
ties within larger business- or management-processes,
but the latter of these is outside of the focus of TORE.
The domain level accommodates as-is and to-be ac-
tivities which refine the tasks by subtasks that con-
tribute to the completion of a stakeholder’s task. Fur-
ther, this level contains system responsibilities (often
called system features), and domain data. The in-
teraction level determines how stakeholders will be
supported in their to-be-activities by the system. Fi-
nally, the system level determines UI details and in-
frastructure including the system architecture. TORE
does not fix or prescribe artifact types for documen-
tation of the DPs. In particular, it is not necessary to
have a separate artifact for every DP, as lower-level
DPs contain decisions for corresponding higher-level
DPs. Several artifact types have often been used, as
is shown in Table 2 by their relation to the DP. The
artifact type task description according to Lauesen’s
Task&Support (Lauesen, 2005) describes stakehold-
ers’ tasks. Subtask templates are used to describe
the DPs As-is and To-be-activities. The DP Domain
Data is described with an UML class diagram or en-
tity relationship diagram, containing domain entities
and their relationships. The UI Structure Diagram
shows the navigation between workspaces for DP UI
Structure, where workspaces group system functions.
Virtual windows (Lauesen, 2005) describe the DP
Screen Structure by an high-level grouping and struc-
turing of the UI data in order to illustrate the informa-
tion needs for tasks early on in the RE process. The
UI Prototype refines the virtual window with the nav-
igation functions and dialogue and documents the DP
UI Data, Dialog and Navigation Functions.
2.4 The Case and Its Context
The case was selected on the basis of availability
as part of the research project Semantic Network of
Information Management in Hospitals (SNIK) (Jahn
et al., 2014). The project team develops, among other
A Task-oriented Requirements Engineering Method for Personal Decision Support Systems - A Case Study
101
Table 2: TORE Decision Point and supported artifact types
relevant for this study (Paech and Kohler, 2004). Rows
marked in grey are introduced in Section 5.
Level Decision Point Artifact
GT Stakeholders Tasks Task description
D As-is activities, To-be
activities
Subtask template
D Domain Data UML class diagram,
ER diagram
D Categorization of ST Task description
D To-be Decision spe-
cific ST
Decision specific
subtask template
I UI Structure UI structure diagram
I System functions Function description
I Interaction Data UML class diagram
I Interaction use case text
G UI Data UI Prototype, Vir-
tual window
G Screen Structure UI Prototype, Vir-
tual window
things (Schaaf et al., 2015), a dashboard for the CIO
of a hospital called CIO-Navigator (CION). The CIO
is the head of the Information Management (IM) De-
partment and is responsible for decision-making in
strategic, tactical, and operational IM. Thus, the CIO
role is located at management or executive level. The
CIO is currently faced with the problem that he strug-
gles with distributed and scattered information in sev-
eral systems and documents. He requires this infor-
mation to make decisions related to the IM and for
each decision the CIO has to collect the necessary
data. By the use of CION, we enable the CIO to nav-
igate current data of the IM department and provide
him with the relevant set of information required for
decision-making of a predefined set of recurring de-
cisions. According to the characteristics presented in
Table 1, CION is a PDSS.
3 RELATED WORK
For related work, we first discuss two papers which
provide an overview of RE for DSSs and then we dis-
cuss goal-oriented RE approaches for DSSs.
Garcia et al. (García et al., 2016) present a com-
prehensive mapping study of 27 articles related to RE
for DSS. Although the title suggests DSSs, the search
terms and the identified literature focus on DW. The
authors conclude that there is a gap in the process of
creating the design of a DSS in a methodical man-
ner. In particular the business needs gain too lit-
tle attention during the RE process. They propose
to elicit business needs from stakeholders by asking
“what do you do and why?”. Another overview by
Salinesi and Gam (Salinesi and Gam, 2009) (not cov-
ered by Garcia et al.) provides a comprehensive dis-
cussion of 15 requirements engineering approaches
for DSSs, all of which are DW-specific. They found
three families of methodological processes. (1) Data-
driven approaches which are focused on the structure
of data sources to design multi-dimensional schemas.
However, these approaches do not cover decision
specifics. (2) Requirement-driven approaches which
focus on decision makers’ requirements. The weak-
ness of these approaches is that the availability of
data sources is not treated sufficiently so that user re-
quirements may not be realizable. (3) Mixed-driven
approaches are a combination of (1) and (2). Both
overviews again confirm the need to understand the
business and stakeholder needs.
As the approaches of both overview papers focus
on DW, they support in particular the specification of
DW data schema definitions, data marts for DWs, and
DW-specific ETL (extract, transform, load) processes,
which are not important for PDSSs. Thus, these new
RE approaches also do not provide a detailed task-
oriented guideline for PDSS development.
There are several goal-oriented RE approaches for
DSS. Again they focus on DW. They share the impor-
tance of the business and decision focus, but focus on
decision specifics for DW such as key performance
indicators (Pourshahid et al., 2014) or business strat-
egy and indicators (Barone et al., 2012; Topaloglou
and Barone, 2015). Giorgini, Rizzi and Garzetti pro-
pose with GRAnD (Giorgini et al., 2008) a goal-
oriented method which connects a decisional model
with a source schema. While this method provides a
detailed analysis of the goals and decisions, it does
not provide guidance for the UI design and early pro-
totyping with the user.
Altogether, we did not find a requirements engi-
neering method for DSS in general and PDSS in par-
ticular which provides guidance for a seamless transi-
tion from the business level to UI details.
4 PROBLEM INVESTIGATION
This section describes the problem investigation, in
which we wanted to understand what decision spe-
cific information is missing in TORE to support the
specification of a PDSS. In particular, we were inter-
ested in those decision details that are necessary for
PDSS requirement specification yet inadequately rep-
resented in TORE’s DPs.
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4.1 Design and Data Collection
We investigated the RE process for the specifica-
tion of CION (cf. Section 2.4) based on the method
TORE. The supported stakeholder (TORE DP Sup-
ported Stakeholder) is the CIO of a particular hos-
pital. Firstly, we performed a pre-assessment of the
tasks and data of the IM department by a combined
task- and system analysis (Ammenwerth et al., 2015)
to gain an overview of the tasks and responsibilities of
the CIO and IM department (Kücherer et al., 2015).
The goal of the CIO is to provide a transparent view
of the operative and tactical data of the IM department
for IT-staff and visitors (documented in the TORE DP
Stakeholders Goals). The resulting artifact was a task
description according to Lauesen’s Task & Support
containing several CIO tasks. In consultation with the
CIO, we prioritized the tasks depending on their im-
portance and selected the first two tasks project man-
agement, and change management for further inves-
tigation. These two tasks were further detailed by
a semi-structured interview (duration 2:15) with the
CIO which helped us to deepen and refine our under-
standing of TORE’s DP Stakeholders Tasks and Do-
main Data wrt decisions. The refined task description
and the meeting minutes were reviewed by the CIO.
During a document analysis based on screen-
shots, we analyzed two spreadsheets provided by the
CIO in order to understand their decision specifics.
These screen shots contained the majority of data nec-
essary for the investigated task project management
and change management. In an additional document
analysis based on operative files, we analyzed further
decision-specific documents in the form of spread-
sheets (cf. Figure 3) and text-documents. The docu-
ment analyses helped us to understand particularly the
decision-specific data. We did not visit the other DPs,
as the insights from these activities already provided
a good picture of the decision-specific requirements.
4.2 Results
The problem investigation shows that TORE’s DP
can capture a large amount of relevant requirements,
which have been gained during the interview. Some
details of important information about the CIO’s de-
cisions cannot be captured explicitly with the exist-
ing artifact types and DPs in TORE, explained in the
following. We identified five decision-specific pieces
of information which we postulate as criteria c
1
-c
5
.
These criteria will shape the treatment design in the
next section.
c
1
: Distinction of decisions from conventional
subtasks. We found subtasks with and without de-
ID: Subtask PM 3a: Prioritize projects of project
list
Actor CIO
Contribution Consider important projects in budget
planning.
Cause Next fiscal year starts in two months
Description Decision about order of new projects for
budget planning. Necessary step before
a project can start. The assigned pri-
ority depends on the project contribu-
tion...
Pre condition all project proposals for next fiscal year
are available. CIO knows goals and ne-
cessity of projects
Info-In urgency, proposed priority of pro-
poser (project proposal), project list,
controlling-list, remaining budget (dif-
ference calculation).
Post condition Changed priorities in project list. Bud-
get is transferred to new project.
Info-Out Priority of new project. Reprioritiza-
tion of existing projects in project list.
Figure 2: Subtask Project Prioritization in standard
template.
cision character. Some subtasks contain a decision
problem as a recurrent choice between several alter-
natives, each of which entails different implications
(cf. example in Sec. 2.2). Such subtasks are in partic-
ular relevant for a PDSS requirements specification.
c
2
: Detailed description of the data necessary to
make the decision. Based on the information from
the pre-assessment and interview, we created the sub-
task description prioritization of projects as
a subtask of the task project management, as is
shown in Figure 2. The documentation with a stan-
dard subtask template does not show explicitly the
data required by a decision. The domain data model
shows the entities, but not the relation between en-
tities and decisions. By way of an example, Fig-
ure 2 shows two deficits: It cannot be explicitly doc-
umented, (a) how the remaining budget is calculated,
i.e. which entity-attribute pairs are used for the calcu-
lation, and (b) which information exactly is necessary
from the project list and the controlling list.
c
3
: Decision-specific rules to choose from al-
ternatives. Decisions always contain alternatives
(cf. Section 2.2). In some cases, the alternatives can
be chosen based on predefined rules. To understand
decisions and their alternatives, it is essential to em-
phasize rules, if there are any. For example, the CIO
explained the rule to assign a priority to new projects.
Projects contributing to service protection receive pri-
ority one, contributions to service operation receive
priority two, and all other projects receive priority
three. This rule is not made explicit in Figure 2.
c
4
: Support of decision-specific patterns in data
for tables and summary fields. The document anal-
A Task-oriented Requirements Engineering Method for Personal Decision Support Systems - A Case Study
103
Running Projects total: 2 Year 2016 95.000 € 50.000 € 90
Pri
o
Proje
ct ID
Title Description
planned
start
planned
budget
assigned
budget
HR
1 15-1 Server Virt. Migration … Q3/2015 120.000 90.000 € 260
16-17 Letter softw. Update phy… Q4/2016 15.000 € 0 € 25
2 16-3 Service Mngr Add KPI … Q2/2016 80.000 € 50.000 € 65
(a) Part of Project List
Project
lead
Proje
ct ID
Assigned
Budget 2016
Remaining
budget
(b) Part of Controlling List
Figure 3: Decision-specific Spreadsheets.
ysis has shown two reoccurring patterns in the data
that is required by the CIO to make a decision. First,
combinations of entity/attribute pairs from more than
one single entity are evident. Second, computed data
such as sums or any other kind of condensed data
is evident. For instance, the CIO needs to priori-
tize new projects, which might change the priority
of existing projects. Currently, for the decision re-
garding the priority of new projects the CIO requires
two documents which he presented to us after the in-
terview: (1) The spreadsheet project list, illus-
trated in Figure 3(a) contains all running, finished,
and planned projects. Each project is specified with
a title and priority, a planned start date, the estimated
budget and Human Resources (HR) effort, and an
approved budget. In the top row, there is the num-
ber of projects and the sum of planned and assigned
budget for projects running in year 2016. (2) The
controlling list which contains an overview of
all projects’ budget status as shown in Figure 3(b),
based on each project’s expenses (not shown here).
The list contains the project’s leader, ID, and title,
as well as the assigned budget in 2016 and the re-
maining budget. Again, there are single rows and
summary fields in the header, such as the total as-
signed budget in 2016 and the total remaining budget
(unused_budget) of all projects. It is important to
describe explicitly and model these decision-specific
data patterns (besides in UI prototypes), in order to
be able to aggregate all data in one model and check
for dependencies and consistencies. The domain data
model does not support the modeling of data combi-
nations from different entities or aggregations.
c
5
: Relation between content, format, and URL
for data sources. The problem investigation has
shown that executives work with spreadsheets con-
taining aggregated data (e.g. Figure 3(a), 3(b)) and
some text-documents. Their content and format is
known to frequent users. Spreadsheets and text-
documents represent heterogeneous decision-specific
data sources. In order to relate the patterns in data
(c
4
) with their origin, we need to document and under-
stand these data sources. As explained in Section 2.2
this heterogeneity is specific to PDSSs. Thus, a de-
tailed description is an important input for system de-
sign decisions. Such a description should contain the
content in terms of entities, the format and the URL.
5 DsTORE - TREATMENT
DESIGN
The design of the DsTORE method addresses the de-
sign problem: Improve the TORE method by decision-
specifics c
1
-c
5
in order to gain a comprehensive and
structured specification for PDSSs. Thus, the em-
phasis is to provide a more precise RE. This sec-
tion presents a short introduction of DsTORE as
TORE enhancement. In this stage, we first intro-
duce new decision-specific DPs with related artifact
types (cf. the right side of Figure 1). In some cases,
we adapt DPs, indicated as dashed DPs in Figure 1.
DsTORE uses the same artifact types as TORE. There
are two extended artifact types, firstly the subtask de-
scription and domain data model, and secondly one
new simple data source model.
5.1 Goal & Task Level
The new decision-specific DP Categorization of sub-
tasks that fulfills criterion c
1
is required to analyze
subtasks with the help of a categorization scheme
in order to find subtasks which are decisions. Two
properties are used for categorization: the presence
of alternatives to choose from and the verb or sub-
stantive of the subtask, indicating a decision. Sub-
tasks can be a decision or a conventional subtask.
For the IM domain, we use a non-exhaustive model
encompassing 7 categories and distinguish objects
or situations (x) and subjects(y). In other domains,
the categorization scheme needs to be populated dif-
ferently. Decisions are Approval of x, Evaluation
of x or y, and Prioritization of x. Conventional
subtasks are Monitoring of x, Documentation of x,
Communication of x to y, and Support of x or y. Ex-
amples are the conventional subtask ’monitoring of
project progress’ classified as M and the decision ’ap-
proval of budget’ with the alternatives rejection or ap-
proval classified as A.
ICEIS 2017 - 19th International Conference on Enterprise Information Systems
104
ID: Subtask PM 3a: Prioritize projects of project list
Actor CIO | Supporting Actors: project leader
Contribution Consider important projects in budget planning.
Cause Next fiscal year starts in two months
Description Decision about order of important projects...
Pre condi-
tion
all project proposals for next fiscal year are avail-
able. CIO knows goals and necessity of projects
Combined
Data
Attribute Entity
project.priority Project List Table Entry
project.start Project List Table Entry
... ...
budget.planned Project List Table Entry
Computed
Data
Attribute Entity Computation
budget.remai-
ning
Controlling
List Ta-
ble Entry
assigned budget -
sum(project ex-
penses)
<derived at-
tribute> un-
used_budget
Controlling
List
sum(budget.re-
maining, all pro-
jects))
Post condi-
tion
Defined order, assigned priority of new projects.
Budget is transferred to new project.
Info out
Attribute Entity
project.priority Project List Table Entry
Rules Priority definition by project contribution: (high)
service protection; (medium) service operation;
(low) nice to have.
Figure 4: Decision Project Prioritization.
5.2 Domain Level
Decision-related subtasks are specified in the DP To-
be decision-specific subtasks and are documented
with the decision-specific subtask template. The
decision-specific subtask template extends TORE’s
subtask template to define the semantics for deci-
sion artifacts and fulfills c
2
and c
3
. It covers de-
tails of a decision in four structured fields, which
are marked yellow in Figure 4. Combined data ex-
press necessary decision- and/or stakeholder-specific
data with entity/attribute pairs. Data aggregations,
e.g. of time or spatial data often used for decision-
making, are documented by computed data and in-
dicated by ’/’ for derived attributes in the Domain
Data Model (cf. Figure 5). Details of the computa-
tions, such as add, subtract, etc., are documented in
the column computation. The result of the deci-
sion is documented in the field Info-out, again with
entity/attribute pairs. Rules describe which alterna-
tive will be chosen by the decision maker and un-
der which circumstances. The notation can be tex-
tual or formal, as is appropriate. Decisions require
specific domain data that is decided in the extended
DP Domain Data which uses additional stereotypes.
The attributes and entities need to be consistent with
those of the decision-specific subtask. The decision-
specific spreadsheets, as presented in the problem in-
vestigation (cf. Section 4), are modeled in the do-
main data with UML stereotypes. Lists, such as
the project list (cf. Figure 3(a)), are modeled by
stereotype «ListEntity». The «ListEntity» is re-
Project
<<ListEntity>>
Project List
projects total
/ sum of planned budget
/ sum of assigned budget
/ sum of man-day
1
0..*
contains planned
and running <
<<View>>
Project List Table
Entry
project.priority (,ID)
...
budget.planned
budget.assigned
project.estimated HR
<<ListEntity>>
Controlling List
account ID
/ sum of planned budget total
/ sum of remaining budget
<<View>>
Controlling List
Table Entry
project.leader
project.ID
project.title
budget.assigned
budget.remaining
Budget
planned
assigned
remaining
1
0..1
has a 
1
0..*
ID
title
leader
description
start
priority
status
...
estimated HR
Ordered List
Figure 5: Part of Domain Data Model for Project
Management.
lated to the listed entities and to a «View» entity
which captures combined attributes. As an exam-
ple, both, the controlling list (cf. Figure 3(b))
and the project list (cf. Figure 3(a)) are modeled
in the domain data model in Figure 5. The class
«ListEntity» Controlling List holds computed
and non-repetitive attributes such as the sum
of planned budget and the sum of remaining
budget (i.e. the unused_budget of other projects)
which are located at the top of the list. The table rows
are modelled by the class «View» Controlling
List Table Entry . Classes of «View» might con-
tain attributes of several domain entities, e.g. the
ID of a project as attribute project.ID and the
remaining budget of the same project as attribute
budget.remaining for Controlling List Table
Entry.
5.3 Interaction Level
In the DP system functions, TORE focuses on the to-
be system functions. DSSs have a limited range of
typical system functions, cf. Holsapple (Holsapple,
2008b), and Power (Power, 2011). Therefore, we add
criterion c
6
: the RE specification should consider typ-
ical PDSS-specific system functions explicitly. Ex-
amples of PDSSs system functions include creation
of reports, navigation to data sources, and document
export. We adapt the DP to use a decision-specific
predefined set of system functions as a guidance to
support completeness and to avoid gold plating. This
set can be adapted according to the different types of
DSS. We also adapt the DP Interaction which is typi-
cally described by use cases. Since PDSSs provide a
dashboard-like UI with one screen for each decision,
a detailed description of interaction on this level is not
necessary. The UI-structure diagram suffices to cap-
ture the navigation between the different workspaces.
A Task-oriented Requirements Engineering Method for Personal Decision Support Systems - A Case Study
105
Table 3: Overview of the Case Study’s activities, duration, and artifact creation effort. (T=Telephone), Duration in [h:mm].
ID Dur. Activity Decision Point / Description
Tasks of Treatment Validation Phase 1: project management, change management
1 1:20 Interview Categorization of Subtasks, To-be Decision Specific Subtask, UI Structure
2 1:20 Interview System Functions, Interaction Data
3 T1:30 Interview System Functions, Interaction Data, UI Data
4 1:45 Interview To-be activities, Domain data, Screen Structure
5 - Development Development of system prototype
6 1:00 Presentation System prototype in software
Tasks of Treatment Validation Phase 2. Task: IT Strategy
7 1:30 Interview Stakeholders Tasks, Categorization of Subtasks, To-be Decision Specific Subtasks, Do-
main Data, Interaction Data
8 1:30 Interview To-be Decision Specific Subtasks, Interaction Data
9 T0:45 Evaluation Eval.: interviews, artifacts, system prototype
5.4 System Level
The DP UI-Data and Screen Structure is documented
with a Virtual Window. Figure 6 shows the Vir-
tual Window of the subtask prioritize projects of
project list (as introduced in Figure 4). The Vir-
tual Window shows the arrangement of the decision-
specific subtask’s data. On the system level, there
is a new DP Data sources. In TORE, data sources
are left to software design. As argued for c
5
the consideration of data sources in DsTORE is
important. Data source description can be cap-
tured in a simple table with the rows entities,
format, and location, e.g. project, excel/csv,
http://filesrv1/2016/project-list.xlsx.
6 CASE STUDY: TREATMENT
VALIDATION
This section describes the design and results of the
two-phase case study to evaluate the treatment design
DsTORE. The case and it’s context is described in
Section 2.4, since it was relevant for the problem in-
vestigation.
Investment budget
plannedavailable
Project
Status
Priority
Change
Planned
Start
Urgent/
Essential
Service budget
Finished Projects
Project
name
Project-
start
Priority,
Date of
change
Project details as above
Project details as above
Status available planned
U
E
Project
ID
Sum Projects
Department budget Year 2016 Year 2015 Year 2014
Plan is
Consumpt.[%]
Plan is
Consumpt.[%]
Plan-is
Consumpt.[%]
investment
budget
Projects /RT
Reserve
Service
budget
IT
devices
IT
organization
Maintenance Hardware
plannedavailable
available planned
Planned Projects
Sum Projects
Running Projects
Sum Projects
Sum Budget
Sum Budget
Figure 6: The virtual window for Project Management.
6.1 Design
The research objective is to identify the extent to
which DsTORE supports the RE of PDSSs. The
object of study is the application of the DsTORE
method. Therefore, we raise RQ.1: How well does
DsTORE support the specification of requirements
for a PDSS? In phase one we re-visted the tasks
project management and change management (al-
ready investigated in the pre-assessment), but now us-
ing DsTORE artifact types for specification. Miss-
ing information was additionally elicited. We used
four semi-structured interviews (activity 1-4) to elicit
the requirements with DsTORE, as shown in Table 3.
DPs visited are: Categorization of subtasks, As-is and
to-be, To-be decision-specific subtasks, UI Structure,
System functions, Interaction data, and Screen Struc-
ture. Table 5 shows which artifacts have been created
after the elicitation during the activities 1-4 and 7-8.
For each artifact the time needed for its creation is
given, including an internal review and a review with
the stakeholder. The task description of project man-
agement and change management were used from the
problem investigation. All other artifacts were newly
created.
The DP Navigation/Supporting Functions was not
relevant, since no supporting functions were neces-
sary. The DP Dialog was not relevant, since the dash-
board does not support complex dialogues. All sys-
tem DPs were refined during the implementation of
the system prototype in activity 5, where two students
implemented a system prototype in .NET which in-
tegrates into SharePoint. We presented this system
prototype to the CIO in activity 6. In phase two
we investigated the CIO task IT-Strategy with activity
7-8. The DPs Stakeholders Task, Categorization of
subtasks, To-be decision-specific subtasks, Decision-
specific domain data, and Interaction data have been
ICEIS 2017 - 19th International Conference on Enterprise Information Systems
106
visited in activity 7. In activity 8 we refined the re-
quirements of DPs To-be decision-specific subtasks,
and Interaction data.
Table 4: Metrics of data collection for the case study - treat-
ment validation.
ID Description of metrics
m1 Time taken for the creation of artifacts
m2 Number & duration of interview sessions in total
m3 Stakeholder’s feedback to the interviews
m4 Stakeholder’s feedback to the artifacts
m5 Stakeholder’s acceptance of the system prototype
m6 Requirements engineer’s feedback
We performed the data analysis for both phases
after all interviews. To answer RQ.1, we used a
Goal Question Metric approach (GQM) (Van Solin-
gen et al., 2002). We study the following effects of
the application of DsTORE (see (Wieringa, 2014) for
similar distinctions): the efficiency in terms of the
time taken for artifact creation and the interviews (m1
and m2), the usability in terms of the ease of use of
the artifacts and the process for the stakeholder (m3
and m4) and the requirements engineer (m6), and the
utility in terms of the value of the outcome for the
stakeholder (m5). The data for these metrics was col-
lected in a semi-structured interview (activity 9). Ta-
ble 4 summarizes the metrics used to answer RQ.1.
6.2 Results
The creation of artifacts (m1) took 106 hrs in phase
one and 7 hrs in phase two, cf. Table 3. Four in-
Table 5: Overview of artifacts created (ID = Activity ID
referring to Table 3, ST=Subtask).
ID Decision Point Artifact Dur.
1
Categorization of ST Task description
56 h
Decision
specific ST
decision-specific ST
UI Structure UI structure diagram
Screen Structure Virtual Window
2
System functions function description
15 h
Interaction Data Domain Data Model
3
System functions UI structure diagram
23 hInteraction Data Domain Data Model
UI Data Virtual Window
4
Interaction UI Prototype
12 hUI Structure UI structure diagram
Screen Structure Virtual Window
7
Stakeholders Tasks Task description
3 h
Categorization of ST Task description
Decision specific ST decision-specific ST
Domain Data Domain Data Model
Interaction Data Domain Data Model
8
Decision specific ST decision-specific ST
4 h
Interaction Data Domain Data Model
Table 6: Metrics and CIO’s artifact rating ( difficult, easy,
◦◦ very easy, ++ very important, + important, - less impor-
tant).
Artifact type simplicity import.
underst. comment underst.
Task description +
Categorization of
subtasks
+
Decision Specific
Task Description
◦◦ +
Data sources ◦◦ ++
Workspaces -
Virtual windows ◦◦ ++
UI Structure Dia-
gram
+
UI Prototype ◦◦ ◦◦ ++
terviews with a duration of approx. 7 hrs. were con-
ducted (m2) in phase one, and two interviews with a
duration of 3 hrs. in phase two. The CIO liked the in-
terviews of both phases and rated the semi-structured
execution of interviews as good (m3), since it gave
him room to discuss ideas. He suggested two im-
provements: the provisioning of a RE-process de-
scription with a graphical sequence upfront, and the
consultation of other departments’ experts in some
situations. The CIO found it sometimes difficult to
provide all relevant decision information. It would
have helped him, if he had a prepared description of
decisions before the RE phase. The meeting minutes
and the correction iteration was good and helpful for
the CIO. The interview preparation and the review
was difficult due to time restrictions. Especially for
phase two, the CIO rated the identification of deci-
sions overall as good. For the task IT-strategy, the
CIO rated the description of decision-related informa-
tion as difficult. He did not want to consider the def-
inition of the IT-strategy as a decision, although the
interview had identified 5 decisions. The CIO’s feed-
back to the artifacts (m4) is summarized in Table 6.
The CIO’s perception of artifacts did not change
between phase one and two. All decision-specific in-
formation was contained in the artifacts. The CIO
perceived the task description as important, and easy
to understand and comment on. However, he con-
sidered the Categorization of Subtasks as difficult to
understand and comment on. Once the categoriza-
tion was done, the CIO understood its importance.
Initially, the CIO did not see the importance of the
Decision-specific Task Description, and hence, rated
the understanding as difficult but easy to comment
on. After the first review of this description, he rated
them as important. He perceived the description of
complex processes (such as decisions) as challeng-
ing. The CIO rated the description of data sources as
very easy to understand, but difficult to comment on
A Task-oriented Requirements Engineering Method for Personal Decision Support Systems - A Case Study
107
(and fill in), since he was not aware of detail knowl-
edge about URLs. The CIO perceived Workspaces
as a complex summary of task details and rated them
as understandable, but unimportant to him, since they
are an intermediate step to virtual windows. The
CIO perceived the UI Structure Diagram as a com-
plex and overloaded representation and rated them
as difficult to understand and comment. He recom-
mends to hide workspace details and focus the nav-
igation between them. The UI Prototype gives the
most detailed description of the system-to-be and al-
lows to check whether the UI contains the necessary
information. It was rated as very easy to understand
and comment and as a very important artifact. The
CIO rated the developed system prototype (m5) as
useful, appropriate, and applicable with a good user
friendliness. However, a more detailed system test is
yet to be done by the CIO to identify missing data
or other gaps. He definitely will employ the proto-
type. The requirements engineer (m6) rated the de-
tailed understanding of the artifact types and their re-
lations to each other as very important to structure the
interviews. The requirements engineer needs to un-
derstand the RE process to choose an appropriate se-
quence of DPs to visit and artifacts to create. During
the RE phase, s/he must keep all artifacts consistent,
which is challenging. The DsTORE artifacts enabled
a detailed understanding of the decisions. The specifi-
cation was extremely helpful to guide the developers
during the implementation of the prototype, in par-
ticular the knowledge of the required data and their
origin. Therefore RQ.1 can be answered as follows:
DsTORE supports the specification of requirements
for a PDSS adequately. It allows an early and contin-
uous stakeholder feedback, emphasizes the decision-
specific data, and decision-specific UI prototyping.
7 DISCUSSION
In this section, we discuss the results of the DsTORE
evaluation and possible improvements to DsTORE, as
well as lessons learned and general experiences with
the method adaptation.
Discussion of DsTORE: The problem investigation
shows that TORE as a structured RE framework pro-
vides the basis for the specification of a PDSS. This
is not surprising as PDSS share some properties with
IS (cf. Table 1). The missing decision-specifics are
provided by DsTORE. Small adaptations in DsTORE
help to understand decisions and to gain a detailed
specification of all PDSS aspects. The treatment val-
idation shows that DsTORE is accepted by the stake-
holder and the requirements engineer, although there
is potential for improvement.
The effort of 106 hrs to create the artifacts is very
high, but decreased significantly in phase two based
on the prior experience. Four interviews with 7 hrs
and two interviews with 3 hrs is a reasonable effort.
Based on the CIO’s feedback, the semi-structured in-
terviews are adequate to elicit requirements and al-
low a creative discussion. The results show that the
CIO views atomic decisions as part of larger business-
or management processes which are also important
to him. It therefore appears interesting to study the
relations of tasks and their atomic decisions to man-
agement processes. The CIO rated only the artifact
workspaces as less important for him. We used the
workspace to structure the virtual windows. In the
future, workspaces might be used only by the require-
ments engineer while the structure is discussed with
the stakeholder directly in the virtual windows. The
CIO’s rating emphasizes the importance of the data
sources and the UI. The CIO’s suggestions do not
concern the DPs, but rather the execution of the inter-
views, which can easily be improved. E.g. decisions
can be identified on the task level with the CIO with-
out specifying details, and can then be detailed with
external experts. The latter can also supply the data
source details. The categorization of subtasks can be
done initially by the requirements engineer and pre-
sented to the CIO for review. The artifacts’ consis-
tency can be improved by a yet to define tool support.
Both, CIO and requirements engineer, missed a RE-
process description covering activities and artifacts.
This can easily be provided in the future.
Lessons Learned: The following sequence is help-
ful for creating some of the artifacts of DsTORE.
(1) task and subtask (2) detailed decision descrip-
tion (3) domain data model (4) virtual windows (5)
workspaces (6) UI Structure Diagram (7) UI Proto-
type. A template for the naming of subtasks should
be used, i.e. <verb | nominalized verbs> <object>.
Synonyms for similar verbs should be avoided. Dur-
ing the elicitation of the to-be decision-specific sub-
task description, it is important to continuously ask
the stakeholder which data exactly is necessary for
the decision. It is important to distinguish explicitly
between domain entities and attributes, as this is not
done directly by the stakeholder. The specification of
rules is often awkward, especially when they are com-
plex, or have not been formulated previously. It was
helpful for us to assure that attributes of rules can be
mapped to the domain data model. It is worth the ef-
fort to assemble the results of the decision description
into virtual windows as early as possible.
General Experiences with Method Adaptation:
During the treatment design we developed several fur-
ICEIS 2017 - 19th International Conference on Enterprise Information Systems
108
ther artifact types, which we finally discarded or sim-
plified, so that they could fit into DsTORE artifact
types. The design science process helped to structure
the adaptation of TORE into problem identification,
specific adaptations, and their evaluation. It forced
us to create explicit justifications for the adaptations.
Further, it forced us to collect explicit feedback from
the stakeholders involved in the method execution. It
is important to discuss the adaptations with indepen-
dent experts not involved in the method execution.
8 THREATS TO VALIDITY
The threats to validity are structured according to
Runeson et al. (Runeson and Höst, 2009). Construct
Validity considers whether the study measures what
it claims. The artifact types of DsTORE were not yet
fixed during phase 1. As all DsTORE DPs as pre-
sented in Section 5 were applied in treatment val-
idation, we believe that the DsTORE artifact types
that have been temporarily used and discarded do not
distort the final results. Internal Validity considers
causal relations of investigated factors, i.e. effects of
unknown factors that influence an investigated fac-
tor. Training obviously affected the effort and the
opinion of the stakeholders. The effort decreased be-
tween the case studies, owing to training effects of the
requirements engineer and CIO. We asked the CIO
about his opinion in activity 9, after he had gained
the experience. The system test and the implementa-
tion of the results of the case study, phase two, might
change the evaluation. However, we consider this as
unlikely. External Validity describes the generaliz-
ability of the findings and the transfer of study results
outside the study. The case studies are based on a sin-
gle case only. The case study involved only one per-
son. DsTORE is specific to PDSSs and the transfer-
ability to other DSS types is unclear. Reliability con-
siders the influence of the specific researcher and in-
dicates threats to validity for a repetition of the study.
The main threat to reliability is that the first author
(as requirements engineer) had much influence on the
development and process of the case study, in partic-
ular during the interviews and the data analysis. We
mitigated this by continuous discussion with the 2nd
researcher.
9 CONCLUSION
In this study, we presented a problem investiga-
tion, DsTORE as the treatment design which extends
TORE to support requirements engineering for PDSS,
and a case study that evaluates DsTORE in the case of
a PDSS, in order to show its basic feasibility. The re-
sults are encouraging to continue with the following
future work: First, we will extend the prototype with
the task IT-strategy. After the system test with the
CIO, this prototype will be put into operation at the
hospital. Second, we will consolidate the improve-
ments of DsTORE as we have sketched above. Third,
as data play a prominent role, we will explore how an
ontology can support the RE process. In carrying out
this last aspect, we rely on the SNIK domain ontol-
ogy (Schaaf et al., 2015) for IM in hospitals. We want
to elaborate, how this knowledge can be used in com-
bination with DsTORE to further improve the require-
ments elicitation and specification. Fourth, we believe
that it would be interesting to investigate whether and
how the presented approach also supports the specifi-
cation of other types of DSSs.
ACKNOWLEDGEMENTS
We thank the involved CIO for his time and moti-
vated collaboration and the SNIK project team for
their intensive cooperation. This work was sup-
ported by DFG (German Research Foundation) under
the Project SNIK: Semantic Network of Information
Management in Hospitals, Grant no. 1605/7-1 and
1387/8-1.
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