from DSSResources.com

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                          DSS News
                       by D. J. Power
               August 12, 2001 -- Vol. 2, No. 17
         A Bi-Weekly Publication of DSSResources.COM

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   Check the DSS Career Center at http://dssresources.com
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Featured:

* DSS Wisdom
* Ask Dan! -- Does data modeling differ for a Data-Driven DSS?
* DSS News Stories

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Each week in the summer, we have about 2700 unique visitors at 
DSSResources.COM. Also, this newsletter has almost 600 subscribers from 
50 countries. Please forward this newsletter to people interested in 
Decision Support Systems or suggest they visit DSSResources.COM and 
subscribe.

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DSS Wisdom

In 1992, Bill Inmon, a pioneer in the field of data warehousing, defined 
a data warehouse as "a collection of integrated, subject-oriented 
databases designed to support the DSS (decision support) function, where 
each unit of data is non-volatile and relevant to some moment in time. 
(p. 5)"

from Inmon, W. H., Building the Data Warehouse, New York: Wiley, 1992.

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IFIP WG 8.3 Conference on Decision Support Systems (DSS),
Decision Support in the Internet Age, Cork, Ireland,
July 4-7, 2002. Paper submissions due November 30, 2001. 
Check http://afis.ucc.ie/dsiage2002/.


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Ask Dan: Does data modeling differ for a Data-Driven DSS?

A conceptual data model shows the overall logical structure of
a database. A data model should be independent of any software or 
data storage structure. In general, a data model is any method for 
visualizing the information needs of a system (check 
http://www.datamodel.org).

Much of the discussion of data modeling uses examples from
transaction processing systems. This makes sense because
much of the formalism of data modeling was developed to reduce data 
redundencies and to avoid anomolies or errors from add, update and 
delete actions in a Database Management System. These issues of 
redundancies and anomalies are not generally relevant when building
Data-Driven DSS with historical data. 

So is data modeling still important when building Data-Driven DSS? YES.

Data modeling organizes a database designer's thinking about the
appropriate structure for the decision support data store. It is still 
useful to think about entities and relationships in a data model to help 
identify data that should be extracted from transaction processing 
systems for decision support.

For example, if we want to monitor and improve decision-making
about product sales we need to look at key entities like
the Customer (a person with attributes), Salesperson 
(a type of employee with attributes), Product (Inventory SKU's),
and Sale (a transaction with attributes like date, time, quantity).

A number of relations help understand the data in the sales transaction 
process: 

-- A customer may have zero or many sales transactions.
-- A particular sale belongs to 1 and only 1 customer. 
-- A particular sale is prepared by no more than 1 salesperson. 
-- A salesperson may have zero or many sales transactions. 
-- A particular sale can have 1 or more products sold. 
-- A product can be sold in 0, 1, or many sales transactions. 

The above relations help a DSS "Data Modeler" understand
what data may be useful to aggregate, what data may benefit
from redundant entries and what data may not be needed for
decision support.

The objective of data modeling is somewhat different when a DSS data 
store is being designed, but one is still trying to gain a rigorous
understanding of how data should be stored in a database before
building and implementing a specific system.

The job title "Data Modeler" is used differently depending on
the company and task environment. A search for "Data Modeler" positions 
in the DSS Career Center indicates that many companies recognize someone 
needs to design and structure a dart mart, data warehouse or DSS data 
store.


Please feel free to comment on differences in modeling data for decision 
support and transaction processing systems.

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The DSSResources.COM DSS Career Center has more than 100 job listings 
for "Data Modeler".  Check openings at John Deere, EMC Corporation, 
Apple Computers, Cap Gemini Ernst & Young, and many other major 
companies.  

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DSS News Stories - July 30 to August 12, 2001

08/12/2001 IBM 5150 PC was introduced on Aug. 12, 1981. Happy 20th 
anniversary.

08/10/2001 SAP Portals certifies SASŪ software interface to Business 
Information Warehouse.

08/08/2001 Leading Japanese computer retailer uses SPSS Clementine to 
improve online profits.

08/08/2001 SPSS Enabling Technologies Division and Azerity form 
strategic alliance.

08/08/2001 PGA of America increases productivity and lowers costs with 
Crystal Decisions reporting.

08/07/2001 MathSoft introduced Web-based Mathcad Client; it enables 
workgroup communication.

08/06/2001 Intranets.com added new document management features 
including web folders for its web-based intranets.

08/01/2001 SAP portals listed as leader in 2H01 Portal Products Magic 
Quadrant.

07/30/2001 Cognos extended Web-Based financial solution with launch of 
Cognos Finance 5.1.

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