DOP8: Merging both data and analysis operators life

DOP8: Merging both data and analysis operators life
cycles for Technology Enhanced Learning
Nadine Mandran, Michael Ortega, Vanda Luengo, Denis Bouhineau
LIG, University of Grenoble 1. Domaine universitaire, BP 46 - 38402 Grenoble Cedex (France)
[email protected]
ABSTRACT
This paper presents DOP8: a Data Mining Iterative Cycle that
improves the classical data life cycle. While the latter only
combines the data production and data analysis phases, DOP8 also
integrates the analysis operators life cycle. In this cycle, data life
cycle and operators life cycle processing meet in the data analysis
step. This paper also presents a reification of DOP8 in a new
computing platform: UnderTracks. The latter provides a flexibility
on storing and sharing data, operators and analysis processes.
Undertracks is compared with three types of platform ’Storage
platform’, ’Analysis platform’ and ’Storage and Analysis
platform’. Several real TEL analysis scenarios are present into the
platform, (1) to test Undertracks flexibility on storing data and
operators and (2) to test Undertracks flexibility on designing
analysis processes.
Categories and Subject Descriptors
J1 [ADMINISTRATIVE DATA PROCESSING/Education],
H.2.8
[DATA
APPLICATIONS/Datamining,
statistical
databases], K3 [COMPUTER AND EDUCATION], D.2.9
[MANAGEMENT/Life cycle].
General Terms
Design, Management, Human Factors, Experimentation
Keywords
process analysis, data life cycle, operators life cycle, flexibility,
sharing, computing platform.
1. INTRODUCTION.
Baker and Siemens [9] underline the importance of increasing the
opportunities for collaborative research and sharing of research
findings between both Educational Data Mining (EDM) and
Learning Analytics Knowledge (LAK) communities. One center
of interest for both communities is the production and the analysis
of data. The two communities have to cope with the data volume
increase, which is becoming an issue for data production.
Moreover, the two communities produce data and operators in
different ways: EDM produces analysis operators that focus on
"automated adaptation, by computer with no human in the loop",
while LAK focuses on "informing and empowering instructors
and learners" [1]. Currently, data and operators are produced in
separate ways, by different communities. The two data life cycles
are then also separated. This separation increases the difficulty in
sharing them, and in providing efficient analysis and relevant
results. One solution to improve collaboration between both
communities is to provide a structure for sharing data as well as
operators and analysis processes. Combining production and data
© 2015 Association for Computing Machinery. ACM acknowledges that this
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LAK '15, March 16 - 20, 2015, Poughkeepsie, NY, USA
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http://dx.doi.org/10.1145/2723576.2723580.
analysis in the same structure means taking into account the two
data life cycles. Roughly speaking, the resulting data life cycle
must consist of three major steps: the design of the study protocol,
the data production and the data analysis
In this paper, we address this issue by providing a new data
mining iterative cycle: DOP8, which combines both data’ life
cycle and operators’ life cycle. This new cycle is reified on a
platform called UnderTracks (UT).
The next section describes related work. The core of our
contribution: respectively the DOP8 cycle and the UT platform
are presented in section 3 and 4. In section 5, the UT platform is
compared to five other platforms, and section 6 discusses about
our proposition.
2. RELATED WORK.
2.1 Data processing schemes
Many data processing are available, and their terminology and
organization are specific to both the activity sector and the
business process they are used for. We focus on three of them,
two of which are designed for educational data mining and one
which is designed for social sciences.
The cycle for applying data mining in educational systems
presented by Romero and Baker [8] proposes two main steps: a
data production step, closely linked to educational systems, and a
data mining step, which combines data mining operators for
showing discovered knowledge to the academics responsible or
the educator, and recommendations to the students.
The processing proposed by Stamper et al. [10] consists of six
steps: Data design, Data collection, Data Analysis, Publish results,
Data archiving, Secondary Analysis (see Figure 1). The latter step
clearly identifies the need for data reuse. However, we consider
that secondary analysis is not a step in a data life cycle, but rather
another goal. Moreover, Stamper et al. indicate a difficulty of
reusing data especially if the metadata are not sufficient. In their
cycle the Data Archiving takes place after the Data Analysis step.
We consider that to ensure efficient data sharing and reuse
metadata should be created at each step of the data life cycle. This
is a mean of keeping all information about data process.
Furthermore, in this cycle the pre-processing step recommended
by Romero et al. [7] is not presented.
Figure 1: Data life cycle described by Stamper et al [10]
Regarding social sciences and humanities, the UK.DATA
ARCHIVE proposes data processing in the form of a data “life”
cycle [2]. This cycle includes six steps: Creating, Processing,
Analyzing, Preserving, Giving access, Reusing. As with the
Romero and Baker cycle [8], the idea of a cycle is interesting
since analysis results can lead to other new issues. This cycle can
be described from a higher level (lower granularity), by grouping
steps: three steps correspond to the data process itself (creating,
processing and analyzing), while the other three steps correspond
to dissemination issues (preserving, accessing and reusing). It can
also be described from a lower level (higher granularity).
After this review, we identify two shortcomings: (1) The
combination between the data processing and the operators
processing is not planned, (2) The platforms are not flexible
enough to integrate and disseminate data, operators and analysis
processes. To address these shortcomings, we propose DOP8 and
we design a structure that enhances the flexibility. Both points are
described in next sections.
3. DOP8
Compared to the latter processing, the first two do not include or
do not detail the pre-processing step, although this step is
important for controlling and enriching the data. These three
processing only focus on data, although the data analysis step also
involves analysis operators. As these operators are usually
developed through three main steps: Design, Development and
Validation, we consider that operators have their own life cycle,
not identified in these three schemes.
2.2 Educational Data and DataMining
Platforms
We classify existing datamining platforms into three categories:
(1) ‘Storage platform’: built to store data and metadata. (2)
‘Analysis platform’: built to analyze data with statistics or data
mining operators. (3) ‘Storage and Analysis platform’: Mixed
platform allow data and operators to be combined.
Verbert et al. analyse three platforms: dataTEL [12], DataShop
[5] and Mulce [6]. While dataTEL and Mulce are ‘Storage
platforms’, PSLC DataShop1 is a ‘Storage and Analysis platform’.
They highlight the strong relationship between the reviewed
platforms and the research questions. DataShop defines a
specification for describing datasets that are derived from
intelligent tutoring systems. This platform then strongly orients
the research questions around “prediction of learner performance
and discovering learner models”. In Mulce, the main research
topic is “Enhancing social learning environments”. With these
platforms it is then difficult to use the same dataset for other
research questions.
Tin Can [15], 'Storage platform', allows flexibility thanks to their
basic format. This approach proposes collecting a Learning
Record Store (LRS) in RDF Format. However, the analysis
operators are not collected or diffused, and the research questions
are not considered. Regarding the ‘Analysis platform‘, platforms
like RapidMiner [13] or Orange [3] are dedicated platforms to
specialists. EDM contains a wide range of specific data mining
algorithms [8] that are not shared in an easy way in these
platforms and they are not dedicated to TEL researches.
DataShop, the only existing ‘Storage and Analysis platform’
proposes operators linked to a specific data type: ITS data. This
platform is mainly dedicated to research works on students’
knowledge and their relation to other domains like collaboration.
For other research questions, DataShop proposes two solutions:
(1) a web-services approach for accessing data, and (2) a storage
space to disseminate externally developed operators. In relation to
the second point, these solutions are “external” solutions, i.e. it is
not possible to associate both, data and external analysis operators
in an easy way.
1
https://pslcdatashop.web.cmu.edu/ResearchGoals?typeId=all
Figure 2: DOP8: Data life cycle and operators life cycle processing
meet in the data analysis step.
The name ‘DOP8’ means: 'Data, Operators and Processes’
combined into a double cycle. Two sub-cycles make up the
DOP8: a cycle describes the data processing and one other
describes the operators processing. Each cycle is split into several
steps. A step is defined with a verb that describes the main actions
of the step. At each step, metadata are generated and stored to
describe the tasks and their results. The metadata can also include
the balance sheet of the task, which describes the weakness and
the strength of each task. Table 1 and 2 presents the goals and the
expected results of both data cycle and operators cycle steps.
Table 1. Goals and expected results for each step of the data cycle.
Step
Prepare
Goals
Design the study to address
the research question.
Collect
Collect the raw data with or
without computer artefacts.
Store them with metadata.
Validate the raw data to
ensure the coherence and
relevance of data. Store it
with metadata.
Convert validated data to
enriched data. Store them
with metadata.
Validate
Enrich
Expected results
Study protocol and
description of raw
data and metadata
for storage
Raw data, metadata
and balance sheet of
study.
Validated data and
metadata
on
validation
Enriched data and
metadata
on
enrichment
Table 2. Goals and expected results for operators’ cycle.
Step
Design
Develop
Validate
Goals
Explore and specify the new
operators for analysing data
Develop the operators from
specifications
Validate and store the
operators for dissemination
Expected results
Specifications
Operational
operators
Validated operators
and metadata on
operators
As presented in Figure 2, the DOP8 cycle proposes to intersect the
two cycles at one step: ‘Analyse’. It combines data and operators
for creating analysis processes, and each cycle benefits from
execution and results of this step. The expected results can be: (1)
interpretation of the results analysis in relation to the research
questions, (2) processes analysis, (3) balance sheet of the study,
and possibly new research questions, (4) balance sheet of the used
operators, and if applicable improvement of them or creation of a
new one.
DOP8 provides a framework to guide the data analysis and
operators development by considering and combining both data
and operators life cycles. To instantiate this framework, we
developed a platform, which allows users (1) to store data,
operators and analysis processes consistently in the same
environment, and (2) to combine the two cycles for providing
flexible data analysis. This platform is described in the next
section.
4. UNDERTRACKS (UT)
Taking into account our work on mandatory metadata, only two
tables are mandatory: “Description” and “Events”. Some data are
mandatory for describing the features of study and events.
In the Description table, the mandatory fields are:
Fields
Name of study
Period of study
Authors
Countries of study
Agent types
Description
The name of the study.
E.g. a date, a year, a semester, …
Names and emails
Country in which the study is conducted
Agents can be of different types (e.g.
student, tutor, group, system, simulator).
Numbers of agents
The number of agents involved
Domain topics
E.g. Chemistry, Mathematics
Production mode: Data are designed with a precise protocol
with or without for addressing a research question or data
study protocol
are produced on the field by the students
or teachers.
In the Events table the mandatory fields are:
UT is an instantiation of DOP8 and is dedicated to TEL
researchers. It proposes two main pieces of software: UTP,
dedicated to the Production of data and operators, and UTA,
dedicated to the Analysis step. UTA allows visual construction of
the analysis processes. UTP and UTA are independent, they
interoperate.
Fields
Timestamp
Agent
Action
4.1 Definitions
UTP provides two ways for storing raw data into its database: (1)
online method, the TEL system is directly connected to UTP; and
(2) offline method, the TEL system saves data into files that are
downloaded into the UTP database afterwards.
An experiment that sets up a DOP8, linked with one or more TEL
systems, is called a “study”. A study involves raw data that is
based on “event” logs: temporally located information. An event
log usually contains the entity responsible for the log, called an
“agent”, that could be a TEL user or the TEL system itself. The
event log also contains an “action” To resume, an event log is a
temporally located information that describes an action from or
between agents. Each algorithm that could be applied on data is
called an “operator”. An operator is an entity that takes input
execution and the results and can provide output data. Operators
can be chained from a raw data to a final result, and this
“workflow” is called an analysis “process”.
4.2 Mandatory Metadata and Fields on UT
Into a ‘Storage platform’, global descriptions of data at a high
level are essential for reusing and sharing data. These descriptions
are usually called ”metadata”. To create useful metadata for
which the time for creation time is not time-consuming [4], we
define a set of mandatory metadata and a set of mandatory fields
(in the sense of a database table). The mandatory metadata
describe the study (see 4.3). The mandatory fields are the
minimum requirements for storing data, operators and processes
into UT to ensure dissemination. Several interviews conducted
with researchers and computer engineers, and based on TEL
researchers’ expertise, have defined these sets. They have been
tested with several studies. Consequently, UT is designed with a
limited number of mandatory metadata and fields.
4.3 UT Production (UTP)
UTP is dedicated to the data and operator production. It allows
UT users to store data, operators and processes and to document
them with metadata. For storing data, five tables are available: 1Description table: for storing the study description, 2- Events
table: for storing the events, 3- Agents table: for describing the
TEL agents, 4- Context table: for describing the context of the
study, 5 - Actions table: for describing the actions.
Description
Date of the event or an ordered value.
Agent that produces events (usually anonymized).
The action produced by the corresponding agent.
4.4 Two ways to import data
4.4.1 Operators
UTP provides an interface for storing operators. Each operator has
two kinds of descriptions:
1. A technical description. This allows both the UTA interface
and the UTA users to know how the operator works and
how it has to be connected with data or other operators,
2. A usage description (operator documentation). This allows
UTA users to know how and why to use it.
In the technical description, all the fields are mandatory. They
mainly describe (1) the input and output data format, and (2) the
parameters that modify the operator’s behavior. In order to ensure
that operators can be used on UT data, the technical description is
closely linked to the data format previously described. In the
current version of UT, the source code of an operator can be in
Java, C++ or Python.
In the ‘Operators table’ the mandatory fields are:
Fields
Name
Category
Description
Owner
Description
Name of the operators
Data management, Data mining, Visualization,
Statistics, or Others.
Description of the operator’s functionalities
Names and mails of process’s owners
4.4.2 Processes
Analysis processes are created from UTA (see 4.5). Two kinds of
data are then stored: (1) The process itself: the process file
consists of a list of operators and data names, with the description
of their links, (2) A process description: created using four
mandatory fields.
In the ‘Processes table’ mandatory fields are:
Fields
Description
Name
Name of the process
Description
The description of the process goals
Names and mails of process’s owners
Whether or not the process is specific for the
TEL researches/data.
4.5 UT Analysis (UTA)
It is a Java application, executed on the client side. This
application is connected to UTP, where it accesses to the current
state of the data, operators and processes description bases. A
UTA user can then graphically connect data and operators to
create a visual workflow (see Figure 4). Once the user decides to
“run” the workflow, UTP sends a textual description of the
process to an engine on the UT server that executes the workflow,
and stores the intermediate. Once the execution is complete, the
user can consult the final and intermediate results. According to
user changes on the workflow description, such as for instance the
raw starting data or simply a parameter that influences the
behavior of one operator’s algorithm, the workflow is
respectively, completely or partially re-executed.
As UT is designed to share and reuse data and processes, UTA
provides a tool for describing and storing new processes into the
UT database. Users can also download existing processes from
UTP in order to execute or modify them.
articles or any additional data describing a study, can be stored
too. The large diversity of these studies illustrates the flexibility of
the UT data structure. Except for the mandatory fields, UT users
create their own structure, in terms of number and name of fields.
The ability to store data from different research domains, different
type of agents, and different sources of data is then possible in the
same database. Moreover, UT currently stores datasets from 8
TEL systems developed in our team TEL systems, as well as from
2 external TEL systems: Tamago cours from Lyon research
TEAM EducTice and Moodle. Data from 14 studies have been
uploaded from text files and 6 systems are directly connected to
UTP.
Table 3. Major differences between DataShop and UnderTracks.
Data
Owners
TEL_specific
MULCE
Tin Can
Storing
RapidMiner Orange
Analysis
DATAShop UnderTracks
Operators
5. UnderTracks vs OTHER PLATFORMS
Mixed
To compare UnderTracks with the Datamining platforms
presented in the related work, we use the DOP8 cycle. In Figure 3,
we then reduce DOP8 to its silhouette, and we blacken the boxes,
which symbolize the steps that the relevant platforms propose.
Mulce and TinCan are specialized in collecting and storing the
data. In Mulce the metadata descriptions are detailed, in particular
for metadata about the study context. However, neither platform
provides guidelines for the ‘Design’ step, in the sense that there is
no online form to guide the design of a study. Neither platform
integrates any step from the operators life cycle. RapidMiner and
Orange are specialized in the operators storing and in data
analysis. They provide a visual programming tool for processes.
Neither platform integrates any step from the data life cycle.
DataShop and UnderTracks store data and operators. Both
platforms provide a space to analyze data. But, there are
differences between the two platforms, the most important of
which are presented in Table 3.
Among the existing platforms, Undertracks is a mixed platform,
such as Datashop. The major difference is the ability of
UnderTracks to integrate data and operators with a degree of
flexibility and to allow UT users to build their own analysis
processes by combining data and operators.
6. UNDERTRACKS FLEXIBILITY
6.1 Diversity of data stored in UTP
The UT data format is flexible enough to store datasets from
different learning domains (already 5 domains: Biology, Maths,
Physics, Medicine and Computer sciences) and different type of
agents (already 4 agent types: students, Tutors, groups of students,
system). UTP stores activity logs, but also heterogeneous data
from specific systems (already 5 data types: Logs, Annotations,
Scores, Eye tracker, Simulator). Additional files, such as papers,
Process
Figure 3: Black boxes represent the steps the platform proposes.
DataShop
UnderTracks
Specific
educational
data,
produced
by
students
interactions
especially with ITS
systems
All kind of TEL data, (e.g.
experimental
annotations,
tracks, haptic and eye tracker)
from several actors: students,
teachers, and systems (e.g.
simulator, ITS, LMS)
Database generic operators
(filter, select), and specific
operators, such as pattern
visualization showed in Figure
8
But also any kind of operators,
Data Mining (e.g. Weka
clustering), statistical (e.g.
crosstab and chi square test)
Database
generic
operators (filter, select),
and specific operators
(e.g. learning curve
[11]) linked with data
stored with DataShop
data structure.
Store external operators
but cannot use them
into the analysis part of
the platform
Use the pre-designed
processes.
Use of pre-designed processes
and ability to design new ones
by combining data, operators
and existing processes
Figure 4: Screenshot of a process created and displayed by UTA. The
blue box is the starting data, while the green and the yellow boxes are
algorithmic and visualization operators respectively. The numbers in
the blacken box indicates the different steps in this analysis process.
6.2 Flexibility of the analysis processes
UTA combines data and operators to design a process. A user can
combine different operators in the same process, either once or
several times. He can also combine different data tables, once or
several times each tabl;e. UT is then flexible in that each element
of the process can be replaced. This kind of flexibility can be
equated with the reuse of operator and analysis processes on
several datasets (see 2.2). For instance, we first tested the process
on a dataset from the Copex-Chimie TEL system (agents are
students, actions are chemical manipulations and lessons readings)
and then on a dataset from the PSLC DataShop platform:
Geometry Area 96 [14]
The goal of this analysis process is to reveal the agent strategy by
visualizing specific action sequences from each agent. The
analysis is split into 4 steps: (1) Visualization of action to explore
the raw data; (2) Computation of the action frequencies to select
the relevant actions addressing the research question; (3) Creation
of patterns with relevant actions, computation of frequencies,
selection and renaming the relevant patterns ; (4) Visualization of
the relevant patterns sequence for visually analyzing the agents’
strategies. This analysis process (see Figure 4) combines one
event data table and seven operators from UnderTracks. Only five
different operators are used: three visualization operators and two
pure algorithmic operators. The visualization operators are used as
leaves of the process workflow, but interactive visualization could
allow these operators to be used also as roots.
Today, as UnderTracks is used by an increasing number of
researchers (in our team but also by one external team), its
number of studies and operators grows fast. Given this situation,
we are currently working on integrating quality indicators for data
sharing. Another challenge is to increase the number of DOP8
steps integrated by UnderTracks, and more precisely the
“prepare” step. One way to simplify and shorten this work is to
guide the TEL researcher. Guiding could start when the researcher
elaborates the study protocol, and could be designed in relation to
the researchers' analysis practices, needs and expectations. To
investigate this subject, an analysis is conducted with researchers
and data analysis experts. Also, we are currently improving UTA
by interoperating with Orange [3] an existing datamining
platform.
8. AKNOWLEDGMENTS
This research has been partially supported by HUBBLE ANR GRANT
number ANR-14-CE24-0015-01, and MOCA ANR, UPMF-9522000392.
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