Characteristics of the Data Warehouse

The Data Warehouse is a database that provides support for decision making.

In simple terms, a data warehouse (DW) is a pool of data produced to support decision making; it is also a repository of current and historical data of potential interest to managers throughout the org.

Integrated

• Integration is closely related to subject orientation. Data warehouses must place data from from different sources into a consistent format. To do so they must deal with naming conflicts and discrepancies among units of measure. A data warehouse is assumed to be totally integrated.

Subject-Oriented

• Data are organised by detailed subject such as sales, products or customers, containing only information relevant for decision support. Enables users to determin not only how the business is performing but why. differs from an operation database in that most operationAL databases have a product orientation and are tuned to handle transactions that update the database. Comprehensive view of the organisation.

Time Variant (time series) (built-in time aspects)

• Maintains historical data. Does not necessarily provide current status (except in real time systems). They detect trends, deviations long-term relationships for forecating and comparrisons, leading to decision making. There is a temporal quality to every data warehouse. Time is the one important dimension that all data warehouses must support. Data for analysis from multiple sources contain multiple time points (daily, weekly, monthly).

Non-Volatile (can't be changed)

• After data are enetered into a data warehouse, users cannot change or update the data. Obsolete data are discarded, and changes are recorded as new data. Enables the data warehouse to be tuned almost exclusively for data access.

Summarized
Not normalized
Sources
Metadata (Data about data)

Why is DSS hard to define? Umbrella term page 21

It is a context free expression that means different things to different people depending on the type of DSS they use.

The term DSS can be used as an umrella term to describe any computerised system that supports decision making in an organisation.

An organisation may have knowledge management systems.......etc

Management Support Systems

Management Support System = MSS.

MSS = The application of technologies to support the performance of management tasks in general.

Sometimes applied more narrowly to Decision Support Systems (DSS) or Business Intelligence (BI).

Caution – MSS, DSS & BI are all sometimes used as context-free umbrella terms**.

Decision Support Systems and Business Intelligence can be considered as subsets of MSS.

Decision Support Systems [DSS] Defined

“A decision support system is a computer based system that is used personally on an ongoing basis by managers and their immediate staff in direct support of managerial activities”

“The term Decision Support System (DSS) has been widely used to refer to systems that are computer-based aids for decision making. Over the years, the term has come to refer to systems that can lend support to decision makers involved in solving problems of some complexity”

“Business Intelligence (BI) Systems are Information Systems that assist managers with unstructured decisions by retrieving and analyzing data in order to identify, generate and interpret useful information. A BI system possesses interactive capabilities, aids in answering ad hoc queries, and provides data and modelling facilities, generally through the use of Online Analytical Processing (OLAP) tools, to support nonrecurring, relatively unstructured decision making.”

Decision Making defined

Decision Making is a process of choosing among two or more alternative courses of action for the purpose of attaining a goal or goals.