Data Warehousing & Data Management Quiz

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Questions and Answers

What term describes the collection of data in a data warehouse that supports management decisions?

  • Web Mining
  • Text Mining
  • Data Mining
  • Data Warehousing (correct)

Which of the following statements about the data warehouse is correct?

  • It can be read and written.
  • It does not support retrieving data.
  • It is read-only. (correct)
  • It is write-only.

What does DSS stand for in the context of Data Warehousing?

  • Decision Support System (correct)
  • Data Support System
  • Decision Single System
  • Data Storable System

What is a key aspect of the data found within a data warehouse?

<p>It is time-variant. (D)</p> Signup and view all the answers

What is typically the time horizon for data stored in a data warehouse?

<p>5-10 years (B)</p> Signup and view all the answers

What describes the type of metadata that defines the structure of data held in operational databases?

<p>Operational metadata (B)</p> Signup and view all the answers

Which type of metadata maps core warehouse metadata to business concepts?

<p>Application level metadata (B)</p> Signup and view all the answers

What type of databases are described as being owned by particular departments or business groups?

<p>Operational (D)</p> Signup and view all the answers

What is the granularity of a fact?

<p>The level of detail at which it is recorded. (D)</p> Signup and view all the answers

Which option is not considered a primary grain in analytical modeling?

<p>Periodic snapshot (A)</p> Signup and view all the answers

Granularity is determined by which factors?

<p>Both A and B (C)</p> Signup and view all the answers

What does it mean for a fact to be fully additive?

<p>It is additive over every dimension. (D)</p> Signup and view all the answers

Which type of fact is defined as being additive over at least one dimension but not all?

<p>Partially additive fact (C)</p> Signup and view all the answers

What does it indicate if a fact is deemed non-additive?

<p>It is not additive across any dimension. (A)</p> Signup and view all the answers

What can non-additive measures be often combined with to create?

<p>Additive measures (C)</p> Signup and view all the answers

What does SQL stand for?

<p>Structured Query Language (C)</p> Signup and view all the answers

What term describes the value that occurs most frequently in a dataset?

<p>Mode (B)</p> Signup and view all the answers

Which graphical representation is specifically designed to display a five-number summary?

<p>Boxplot (D)</p> Signup and view all the answers

Which of the following describes an active data warehouse architecture?

<p>At least one data mart with near real-time updates (B)</p> Signup and view all the answers

What characteristic best defines transient data within data management?

<p>Data records that are eliminated upon changes (A)</p> Signup and view all the answers

What is the primary purpose of data scrubbing?

<p>To clean and improve data quality (B)</p> Signup and view all the answers

An ordinal variable can be best described as:

<p>A qualitative variable that has a meaningful order (A)</p> Signup and view all the answers

Which type of attribute is characterized by having a finite or countably infinite set of values?

<p>Discrete attribute (B)</p> Signup and view all the answers

Which of the following is true about data objects?

<p>They are defined by the attributes that characterize them (C)</p> Signup and view all the answers

Which statement accurately describes the role of dimensionality reduction?

<p>It reduces the dataset size by removing irrelevant attributes. (C)</p> Signup and view all the answers

Which term is used to describe the independence of one attribute's effect on a class from the values of other attributes?

<p>Conditional independence (C)</p> Signup and view all the answers

What is the primary reason for organizations to implement a data warehouse?

<p>To facilitate the storage of a large volume of data. (C)</p> Signup and view all the answers

What alternative term is used for a multidimensional database?

<p>DBMS (A)</p> Signup and view all the answers

Which database architecture forms the foundation of data warehouse architecture?

<p>Relational DBMS (D)</p> Signup and view all the answers

From where does the source data in a data warehouse typically originate?

<p>Operational Data Store (A)</p> Signup and view all the answers

Which process signifies a data transformation method within a database?

<p>Filtering (D)</p> Signup and view all the answers

What does metadata refer to in the context of databases?

<p>Data about data (B)</p> Signup and view all the answers

What does the load and index process primarily involve?

<p>A process to load the data in the data warehouse and to create the necessary indexes. (A)</p> Signup and view all the answers

Which of the following best describes data transformation?

<p>A process to change data from a detailed level to a summary level. (D)</p> Signup and view all the answers

Which process is referred to as multifield transformation?

<p>Converting data from one field into multiple fields. (B)</p> Signup and view all the answers

What type of relationship is typically found in a star schema?

<p>One-to-many. (A)</p> Signup and view all the answers

Which statement about fact tables is true?

<p>Completely normalized. (C)</p> Signup and view all the answers

In the context of Business Intelligence, which function relates to the role of data warehousing?

<p>All of the above. (D)</p> Signup and view all the answers

Which function is not supported by the data administration subsystem?

<p>Create, change, and delete information. (B)</p> Signup and view all the answers

What is the most common source of change data for refreshing a data warehouse?

<p>Queryable change data. (C)</p> Signup and view all the answers

What characterizes an outlier in a data set?

<p>A data object that significantly differs from other observations (C)</p> Signup and view all the answers

Which statement about correlation and causality is true?

<p>Causality can exist without any correlation (B)</p> Signup and view all the answers

Which of the following best describes a boxplot?

<p>A visualization summarizing a set of data through quartiles (A)</p> Signup and view all the answers

What are the main tasks involved in data preprocessing?

<p>Data cleaning, data integration, data reduction, and data transformation (A)</p> Signup and view all the answers

In database terminology, what is a star schema?

<p>A fact table surrounded by multiple dimension tables (C)</p> Signup and view all the answers

Which of the following is NOT a type of data mart?

<p>Distributed data mart (A)</p> Signup and view all the answers

Which term refers to data that defines warehouse objects?

<p>Meta data (D)</p> Signup and view all the answers

What format does OLAP stand for?

<p>On-Line Analytical Processing (C)</p> Signup and view all the answers

Flashcards

Data object

A data object is a representation of an entity, such as a customer, product, or order. It encapsulates all the relevant information about that entity.

Attributes of a data object

Attributes are characteristics or properties that describe a data object. Each attribute represents a specific aspect of the object, such as name, age, or price.

Mode (Data)

The mode is the value that appears most frequently in a dataset. It indicates the most common observation in the data.

Boxplot

A boxplot is a graphical representation of a dataset's five-number summary. It displays the minimum, first quartile, median, third quartile, and maximum values of the data.

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Histogram

A histogram is a graphical representation of data where the x-axis represents the values and the y-axis represents their corresponding frequencies. The bars in the histogram depict the frequency distribution of the data.

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Ordinal variable

An ordinal variable is a type of variable that has a natural order or ranking. It can be discrete, having a finite number of values, or continuous, with an infinite number of values within a range.

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Document as a data object

A document can be represented as a data object with thousands of attributes that capture its content, structure, and other relevant information.

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Scatter plot

A scatter plot is a graph that depicts the relationship between two variables using points. Each point represents a pair of values, plotted as coordinates in a two-dimensional plane.

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Dimensionality Reduction

Removing irrelevant attributes from the dataset to reduce its size while preserving essential information.

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Value Independence

An attribute's effect on a class doesn't depend on other attribute values.

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Data Warehouse Justification

A data warehouse's primary purpose is to support decision-making by storing large amounts of historical data.

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Multidimensional Database

A multidimensional database, also known as a relational database management system (RDBMS), is designed to store and analyze data with multiple dimensions, making it ideal for data warehousing.

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Data Warehouse Architecture

Data warehouses typically use relational database management systems as their core architecture, providing structured data storage and retrieval.

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Data Warehouse Source

The primary source of data for data warehouses is often operational data stores (ODS), where transactional data is collected and processed.

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Data Transformation: Filtering

Filtering is a data transformation process that selectively eliminates data based on specific criteria.

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Multidimensional Database Purpose

Multidimensional databases are designed to overcome limitations of relational models, providing better support for data warehousing and analysis.

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Granularity of a fact

The level of detail at which data is recorded.

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Fully additive fact

A fact is fully additive if it can be summed up across any of its dimensions.

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Partially additive fact

A fact is partially additive if it can be summed up across some of its dimensions, but not all.

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Non-additive fact

A fact is non-additive if it cannot be summed up across any of its dimensions.

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Functional dependency

The property that all attributes of an entity depend on the entire primary key.

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SQL

A database query language used to access and manipulate data.

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OLAP

A type of data processing that focuses on analyzing large amounts of data to gain business insights.

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Multidimensional data

Data that can be categorized into dimensions and measures.

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Load and Index: What is it?

A process involving loading data into a data warehouse and creating necessary indexes for efficient data retrieval.

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Data Transformation: What is it?

Transforming data from a detailed level to a summarized level, essentially condensing information for easier analysis.

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Multifield Transformation: What is it?

A type of data conversion that involves changing data from one field into multiple fields.

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Star Schema: What is the relationship?

A database design where data is organized into fact tables and dimension tables. The relationship between the fact table and dimension tables is one-to-many.

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Fact Tables: What is their normalization?

Fact tables in a star schema are fully normalized, meaning data is organized efficiently and avoids redundancy.

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BI and Data Warehousing: What are they used for?

Business Intelligence (BI) and data warehousing are used for forecasting future trends, data mining to extract insights from data, and analyzing large volumes of data.

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Data Administration Subsystem: What does it do?

The data administration subsystem is responsible for managing data in a warehouse, but it does not directly create, change, or delete information.

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Refreshing a Data Warehouse: What is the most common source of change data?

Queryable change data is the most common source for refreshing data in a warehouse. This means data changes are tracked and can be used to update the warehouse.

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What is a data warehouse?

A subject-oriented, integrated, time-variant, nonvolatile collection of data used to support management decisions.

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Is a data warehouse read only or write only?

Data warehouses are designed for read-only operations. Data is extracted, transformed, and loaded (ETL) for analytical purposes.

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What does DSS stand for in the context of a data warehouse?

Decision Support System (DSS). It refers to systems that help users make informed decisions by providing analytical capabilities.

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What are the key characteristics of a data warehouse?

Data warehouses are subject-oriented, time-variant, and integrated. This means they organize data around business topics, track changes over time, and combine data from multiple sources.

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What is the typical time horizon for data stored in a data warehouse?

Data warehouses typically store data for an extended period, often spanning from 5 to 10 years, to analyze trends and patterns over time.

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What is OLTP and why is it different from a data warehouse?

Online Transaction Processing (OLTP) systems handle real-time transactions and update data frequently. They are used for day-to-day business operations.

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What is metadata in a data warehouse?

Metadata describes the data stored in the data warehouse. It provides information about the data's structure, meaning, and origin.

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What is the heart of a data warehouse?

Data warehouse database servers are the central component, storing and managing the data for analytical queries.

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Outlier

A data point that significantly deviates from the general pattern or behavior of the dataset. It can be caused by errors, unusual events, or simply the inherent variability of the data.

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Data Integration

The process of collecting, storing, and organizing data from various sources in a way that makes it readily available and useful for analysis.

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Data Reduction

The process of reducing the size of a dataset without losing significant information. This can be achieved by techniques like data aggregation, feature selection, or dimensionality reduction.

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Data Discretization

A type of data transformation that involves converting data from a continuous scale to a discrete scale. This can be useful for simplifying data analysis or for creating categorical features.

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Data Warehouse

A database designed for analytical reporting and decision making. It typically stores historical data from multiple sources, making it suitable for exploring trends and patterns over time.

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Data Mart

A type of data warehouse designed for specific business needs, often with a smaller scope and faster query performance.

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Star Schema

A data structure used in data warehousing that represents data in a multidimensional fashion, allowing for slice-and-dice analysis. It consists of a fact table in the center surrounded by dimension tables.

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Meta data

Data that describes other data. It provides information about the structure, content, and context of a dataset. This can be used for metadata management, data governance, and data quality control.

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Study Notes

DWH&DM

  • DWH&DM is a subject-oriented, integrated, time-variant, nonvolatile collection of data to support management decisions.
  • Data Warehouse is read-only.
  • Expansion for DSS in DW is Decision Support System.
  • Important aspects about data found within a Data Warehouse environment include: subject-oriented, time-variant, and integrated.
  • Time horizon in a Data Warehouse is usually 5-10 years.
  • Data is stored, retrieved, and updated in OLAP.
  • Metadata describes data in the warehouse.
  • Data warehouse database servers are the heart of the warehouse.

Operational vs. Data Warehouse Data

  • Operational systems are used for real-time business operations and are based on current data.
  • Data Warehouse is based on historical data used for decision support.

Data Warehouse Architecture

  • Active Data Warehouse Architecture includes: having at least one data mart, data extracted from numerous internal and external sources, and near real-time updates.
  • Data stored in various operational systems throughout the organization
  • Data stored in one operational system for end-user support applications is current data.

Data Transformation

  • Data Transformation is a process of changing data from a detailed level to a summary level or vice versa.
  • Data from one source can combine into various sources.
  • Data from multiple fields can convert into one field.

Data Summarization

  • Transformations of data from one level to another.
  • Aggregating data at a specified level to summarize.

Data Warehousing Tools and Techniques

  • Metadata are data about data, which contain the structure, algorithms for summarization, and a map describing the warehouse's relationship with the operational environment.
  • Dimensionality reduction removes irrelevant attributes to reduce data set size.
  • Finding and removing duplicate or outdated data is known as data scrubbing.
  • Business Intelligence, data mining, and analysis of large volumes of data are data operations.

Data Preprocessing Tasks

  • Data cleaning (handling missing or incorrect data, removing duplicates, validating data accuracy).
  • Data integration (combining data from different sources).
  • Data transformation (converting data to a common format).
  • Data reduction (reducing data size for easier processing).

Data Warehousing Concepts

  • Data warehousing is used to support decision-making.
  • Data is used for reporting and analysis.
  • The data warehouse is a separate system from the operational database.
  • Key business aspects of data.
  • Data marts and data warehouses.
  • Data warehouse tools.

Data Attributes

  • Data objects are described by attributes.
  • Different types of attributes exist: such as nominal, binary, ordinal.
  • Calculating summary measures like mode, median, mean, boxplots and quantile plots describe data insights.

Data Visualization

  • In data visualization graphs and charts are used to discover summary measures of data and interpret analysis.

Data Quality

  • Data quality: ensures data completeness, accuracy, and consistency for reliable reporting.
  • It is essential for a reliable data warehouse.

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