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<title>Assessment Data Model Overview</title>
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<h2>Overview</h2>
<p>
At its core, the Assessment package defines a hierarchical container
model of a "survey", "questionnaire" or "form". This approach not only
follows the precedent of existing work; it also makes excellent sense
and no one has come up with a better idea.
</p>
<p></p>
<ul>
<li> One Assessment consists of
</li>
<li> One or more Sections which each consist of
</li>
<li> One or more Items which have </li>
<li> Zero or more Choices
</li>
</ul>
<p>We choose the terms Assessment-Sections-Items-Choices over
Surveys-Sectdions-Questions-Choices partly to reduce naming clashes
during the transition from Survey/Questionnaire packages, but mostly
because these terms are more general and thus suit the broader
applicability intended for this package.
</p>
<p>As is the custom in the OpenACS framework, all RDBMS tables in
the package will be prepended with "as_" to prevent further prevent
naming clashes. Judicious use of namespaces will also be made in
keeping with current OpenACS best practice.
</p>
<p>Several of the Metadata entities have direct counterparts in
the Data-related partition of the data model. Some standards (notably
CDISC) rigorously name all metadata entities with a "_def" suffix and
all data entities with a "_data" suffix -- thus "as_item_def" and
"as_item_data" tables in our case. We think this is overkill since
there are far more metadata entities than data entities and in only a
few cases do distinctions between the two become important. In those
cases, we will add the "_data" suffix to data entities to make this
difference clear.
</p>
<p>A final general point (that we revisit for specific entities
below): the Assessment package data model exercises the Content
Repository (CR) in the OpenACS framework heavily. In fact, this use of
the CR for most important entities represents one of the main advances
of this package compared to the earlier versions. The decision to use
the CR is partly driven by the universal need for versioning and reuse
within the functional requirements, and partly by the fact that the CR
has become "the Right Way" to build OpenACS systems. Note that one
implication of this is that we can't use a couple column names in our
derived tables because of naming clashes with columns in cr_items and
cr_revisions: title and description. Furthermore, we can handle <a
href="versioning.html">versioning</a> and internationalization through
the CR. </p>
<p></p>
<h2>Synopsis of The Data Model</h2>
<p>
Here's a detailed summary view of the entities in the Assessment
package. Note that in addition to the partitioning of the entities
between Metadata Elements and Collected Data Elements, we identify the
various subsystems in the package that perform basic functions.
</p>
We discuss the following stuff in detail through the subsequent
pages, and we use a sort of "bird's eye view" of this global graphic to
keep the schema for each subsystem in perspective while homing in on
the relevant detail. Here's a brief introduction to each of these
section<br>
<p></p>
<ul>
<li> <a href="as_items.html">core - items</a> entities (purple)
define the structure and semantics of Items, the atomic units of the
Assessment package
</li>
<li> <a href="grouping.html">core - grouping</a> entities (dark
blue) define constructs that group Items into Sections and Assessments</li>
<li> <a href="sequencing.html">sequencing </a>entities
(yellow-orange) handle data validation steps and conditional navigation
derived from user responses
</li>
<li> <a href="sequencing.html">scoring ("grading")</a> entities
(yellow-green) define how raw user responses are to be processed into
calculated numeric values for a given Assessment
</li>
<li> <a href="display_types.html">display </a>entities (light blue)
define constructs that
handle how Items are output into the actual html forms returned to
users for completion -- including page layout and internationalization
characteristics
</li>
<li> <a href="policies.html">scheduling </a>entities define
mechanisms for package administrators to set up when, who and how often
users should perform an Assessment
</li>
<li> <a href="data_collection.html">session data collection</a>
entities (bright green) define
entities that store information about user data collection events --
notably session status and activities that change that status as the
user users the system</li>
</ul>
<center><a
href="http://openacs.org/storage/download/assessment.graffle?version_id=187542"></a>
<p><img alt="Data Model Graphic" src="images/assessment.jpg"
style="width: 1076px; height: 1442px;"></p>
</center>
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