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Sunday, July 14, 2013

DATA WAREHOUSING AND DATA MINING,2Mark,Unit V



1.What are the classifications of tools for data mining?

• Commercial Tools
• Public domain Tools
• Research prototypes

2.What are commercial tools?

Commercial tools can be defined as the following products and usually are
associated with the consulting activity by the same company:
1. ‘Intelligent Miner’ from IBM
2. ‘SAS’ System from SAS Institute
3. ‘Thought’ from Right Information Systems. Etc
  
3. What are Public domain Tools?

Public domain Tools are largely freeware with just registration fees:
’Brute’ from University of Washington. ‘MC++’ from Stanford university, Stanford,
California.

4. What are Research prototypes?

Some of the research products may find their way into commercial
market: ‘DB Miner’ from Simon Fraser University, British Columbia, ‘Mining Kernel
System’ from University of Ulster, North Ireland.

 5.What is the difference between generic single-task tools and generic multi-task
tools?

Generic single-task tools generally use neural networks or decision trees.
They cover only the data mining part and require extensive pre-processing and postprocessing
steps.

Generic multi-task tools offer modules for pre-processing and postprocessing
steps and also offer a broad selection of several popular data mining
algorithms as clustering.

6. What are the areas in which data warehouses are used in present and in future?

The potential subject areas in which data ware houses may be developed at
present and also in future are

1.Census data:
The registrar general and census commissioner of India decennially
compiles information of all individuals, villages, population groups, etc. This information
is wide ranging such as the individual slip. A compilation of information of individual
households, of which a database of 5%sample is maintained for analysis. A data
warehouse can be built from this database upon which OLAP techniques can be applied,
Data mining also can be performed for analysis and knowledge discovery

2.Prices of Essential Commodities
The ministry of food and civil supplies, Government of India complies
daily data for about 300 observation centers in the entire country on the prices of
essential commodities such as rice, edible oil etc, A data warehouse can be built
for this data and OLAP techniques can be applied for its analysis

7. What are the other areas for Data warehousing and data mining?
• Agriculture
• Rural development
• Health
• Planning
• Education
• Commerce and Trade

8. Specify some of the sectors in which data warehousing and data mining are used?

• Tourism
• Program Implementation
• Revenue
• Economic Affairs
• Audit and Accounts

9. Describe the use of DBMiner.

Used to perform data mining functions, including characterization,
association, classification, prediction and clustering.
                                                            
10. Applications of DBMiner.

The DBMiner system can be used as a general-purpose online analytical
mining system for both OLAP and data mining in relational database and
datawarehouses.
Used in medium to large relational databases with fast response time.

11. Give some data mining tools.
DBMiner
GeoMiner
Multimedia miner
WeblogMiner

12. Mention some of the application areas of data mining

DNA analysis
Financial data analysis
Retail Industry
Telecommunication industry
Market analysis
Banking industry
Health care analysis.

13. Differentiate data query and knowledge query

A data query finds concrete data stored in a database and corresponds to a
basic retrieval statement in a database system.
A knowledge query finds rules, patterns and other kinds of knowledge in a
database and corresponds to querying database knowledge including
deduction rules, integrity constraints, generalized rules, frequent patterns and
other regularities.

 14.Differentiate direct query answering and intelligent query answering.

Direct query answering means that a query answers by returning exactly what
is being asked.
Intelligent query answering consists of analyzing the intent of query and
providing generalized, neighborhood, or associated information relevant to the
query.

15. Define visual data mining

Discovers implicit and useful knowledge from large data sets using data and/
or knowledge visualization techniques.Integration of data visualization and data mining.

16. What does audio data mining mean?

Uses audio signals to indicate patterns of data or the features of data mining
results.Patterns are transformed into sound and music.
To identify interesting or unusual patterns by listening pitches, rhythms, tune
and melody.
Steps involved in DNA analysis
Semantic integration of heterogeneous, distributed genome databases
Similarity search and comparison among DNA sequences
Association analysis: Identification of co-occuring gene sequences
Path analysis: Linking genes to different stages of disease development
Visualization tools and genetic data analysis

17.What are the factors involved while choosing data mining system?
Data types
System issues
Data sources
Data Mining functions and methodologies
Coupling data mining with database and/or data warehouse systems
Scalability
Visualization tools
Data mining query language and graphical user interface.


18. Define DMQL
Data Mining Query Language
It specifies clauses and syntaxes for performing different types of data mining
tasks for example data classification, data clustering and mining association
rules. Also it uses SQl-like syntaxes to mine databases.


19. Define text mining
Extraction of meaningful information from large amounts free format textual
data.
Useful in Artificial intelligence and pattern matching
Also known as text mining, knowledge discovery from text, or content
analysis.

20. What does web mining mean
Technique to process information available on web and search for useful data.
To discover web pages, text documents , multimedia files, images, and other
types of resources from web.
Used in several fields such as E-commerce, information filtering, fraud
detection and education and research.

21.Define spatial data mining.
Extracting undiscovered and implied spatial information.
Spatial data: Data that is associated with a location
Used in several fields such as geography, geology, medical imaging etc.

22. Explain multimedia data mining.
Mines large data bases.
Does not retrieve any specific information from multimedia databases
Derive new relationships , trends, and patterns from stored multimedia data
mining.
Used in medical diagnosis, stock markets ,Animation industry, Airline
industry, Traffic management systems, Surveillance systems etc.

DATA WAREHOUSING AND DATA MINING,2Mark,Unit IV



1.Define data warehouse?
A data warehouse is a repository of multiple heterogeneous data sources
organized under a unified schema at a single site to facilitate management decision
making .
(or)
A data warehouse is a subject-oriented, time-variant and nonvolatile
collection of data in support of management’s decision-making process.

2.What are operational databases?
Organizations maintain large database that are updated by daily transactions are
called operational databases.

3.Define OLTP?
If an on-line operational database systems is used for efficient retrieval, efficient
storage and management of large amounts of data, then the system is said to be on-line
transaction processing.

4.Define OLAP?
Data warehouse systems serves users (or) knowledge workers in the role of data
analysis and decision-making. Such systems can organize and present data in various
formats. These systems are known as on-line analytical processing systems.

5.How a database design is represented in OLTP systems?
Entity-relation model

6. How a database design is represented in OLAP systems?
Star schema
Snowflake schema
Fact constellation schema

7.Write short notes on multidimensional data model?
Data warehouses and OLTP tools are based on a multidimensional data model.
This model is used for the design of corporate data warehouses and department data
marts. This model contains a Star schema, Snowflake schema and Fact constellation
schemas. The core of the multidimensional model is the data cube.

8.Define data cube?
It consists of a large set of facts (or) measures and a number of dimensions.

9.What are facts?
Facts are numerical measures. Facts can also be considered as quantities by which
we can analyze the relationship between dimensions.

10.What are dimensions?
Dimensions are the entities (or) perspectives with respect to an organization for
keeping records and are hierarchical in nature.

11.Define dimension table?
A dimension table is used for describing the dimension.
(e.g.) A dimension table for item may contain the attributes item_ name, brand and type.

12.Define fact table?
Fact table contains the name of facts (or) measures as well as keys to each of the
related dimensional tables.

13.What are lattice of cuboids?
In data warehousing research literature, a cube can also be called as cuboids. For
different (or) set of dimensions, we can construct a lattice of cuboids, each showing the
data at different level. The lattice of cuboids is also referred to as data cube.

14.What is apex cuboid?
The 0-D cuboid which holds the highest level of summarization is called the apex
cuboid. The apex cuboid is typically denoted by all.

15.List out the components of star schema?
 A large central table (fact table) containing the bulk of data with no
redundancy.
_ A set of smaller attendant tables (dimension tables), one for each
dimension.

16.What is snowflake schema?
The snowflake schema is a variant of the star schema model, where some
dimension tables are normalized thereby further splitting the tables in to additional tables.

17.List out the components of fact constellation schema?
This requires multiple fact tables to share dimension tables. This kind of schema
can be viewed as a collection of stars and hence it is known as galaxy schema (or) fact
constellation schema.

18.Point out the major difference between the star schema and the snowflake
schema?
The dimension table of the snowflake schema model may be kept in normalized
form to reduce redundancies. Such a table is easy to maintain and saves storage space.
 
19.Which is popular in the data warehouse design, star schema model (or)
snowflake schema model?
Star schema model, because the snowflake structure can reduce the effectiveness
and more joins will be needed to execute a query.

20.Define concept hierarchy?
A concept hierarchy defines a sequence of mappings from a set of low-level
concepts to higher-level concepts.

21.Define total order?
If the attributes of a dimension which forms a concept hierarchy such as
“street
Country
Province or state
City
Street
Fig: Partial order for location
22.Define partial order?
If the attributes of a dimension which forms a lattice such as
“day<{month
23.Define schema hierarchy?
A concept hierarchy that is a total (or) partial order among attributes in a database
schema is called a schema hierarchy.
24.List out the OLAP operations in multidimensional data model?
_ Roll-up
_ Drill-down
_ Slice and dice
_ Pivot (or) rotate

25.What is roll-up operation?
The roll-up operation is also called drill-up operation which performs aggregation
on a data cube either by climbing up a concept hierarchy for a dimension (or) by
dimension reduction.

26.What is drill-down operation?
Drill-down is the reverse of roll-up operation. It navigates from less detailed data
to more detailed data. Drill-down operation can be taken place by stepping down a
concept hierarchy for a dimension.

27.What is slice operation?
The slice operation performs a selection on one dimension of the cube resulting in
a sub cube.

28.What is dice operation?
The dice operation defines a sub cube by performing a selection on two (or) more
dimensions.

29.What is pivot operation?
This is a visualization operation that rotates the data axes in an alternative
presentation of the data.

30.List out the views in the design of a data warehouse?
_ Top-down view
_ Data source view
_ Data warehouse view
_ Business query view

31.What are the methods for developing large software systems?
_ Waterfall method
_ Spiral method

32.How the operation is performed in waterfall method?
The waterfall method performs a structured and systematic analysis at each step
before proceeding to the next, which is like a waterfall falling from one step to the next.

33.How the operation is performed in spiral method?
The spiral method involves the rapid generation of increasingly functional
systems, with short intervals between successive releases. This is considered as a good
choice for the data warehouse development especially for data marts, because the turn
around time is short, modifications can be done quickly and new designs and
technologies can be adapted in a timely manner.

34.List out the steps of the data warehouse design process?
_ Choose a business process to model.
_ Choose the grain of the business process
_ Choose the dimensions that will apply to each fact table record.
_ Choose the measures that will populate each fact table record.

35.Define ROLAP?
The ROLAP model is an extended relational DBMS that maps operations on
multidimensional data to standard relational operations.

36.Define MOLAP?
The MOLAP model is a special purpose server that directly implements
multidimensional data and operations.

37.Define HOLAP?
The hybrid OLAP approach combines ROLAP and MOLAP technology,
benefiting from the greater scalability of ROLAP and the faster computation of
MOLAP,(i.e.) a HOLAP server may allow large volumes of detail data to be stored in a
relational database, while aggregations are kept in a separate MOLAP store.

38.What is enterprise warehouse?
An enterprise warehouse collects all the information’s about subjects spanning the
entire organization. It provides corporate-wide data integration, usually from one (or)
more operational systems (or) external information providers. It contains detailed data as
well as summarized data and can range in size from a few giga bytes to hundreds of giga
bytes, tera bytes (or) beyond. An enterprise data warehouse may be implemented on
traditional mainframes, UNIX super servers (or) parallel architecture platforms. It
requires business modeling and may take years to design and build.

39.What is data mart?
Data mart is a database that contains a subset of data present in a data warehouse.
Data marts are created to structure the data in a data warehouse according to issues such
as hardware platforms and access control strategies. We can divide a data warehouse into
data marts after the data warehouse has been created. Data marts are usually implemented
on low-cost departmental servers that are UNIX (or) windows/NT based. The
implementation cycle of the data mart is likely to be measured in weeks rather than
months (or) years.

40.What are dependent and independent data marts?
Dependent data marts are sourced directly from enterprise data warehouses.
Independent data marts are data captured from one (or) more operational systems (or)
external information providers (or) data generated locally with in particular department
(or) geographic area.
41.What is virtual warehouse?
A virtual warehouse is a set of views over operational databases. For efficient
query processing, only some of the possible summary views may be materialized. A
virtual warehouse is easy to build but requires excess capability on operational database
servers.

42.Define indexing?
Indexing is a technique, which is used for efficient data retrieval (or) accessing
data in a faster manner. When a table grows in volume, the indexes also increase in size
requiring more storage.

43.What are the types of indexing?
_ B-Tree indexing
_ Bit map indexing
_ Join indexing

44.Define metadata?
Metadata is used in data warehouse is used for describing data about data.
(i.e.) meta data are the data that define warehouse objects. Metadata are created for the
data names and definitions of the given warehouse.

45.Define VLDB?
Very Large Data Base. If a database whose size is greater than 100GB, then
the database is said to be very large database.

DATA WAREHOUSING AND DATA MINING,2Mark,Unit III



1.Define Clustering?
Clustering is a process of grouping the physical or conceptual data object into
clusters.

2. What do you mean by Cluster Analysis?
A cluster analysis is the process of analyzing the various clusters to organize the
different objects into meaningful and descriptive objects.

3. What are the fields in which clustering techniques are used?
• Clustering is used in biology to develop new plants and animal
taxonomies.
• Clustering is used in business to enable marketers to develop new
distinct groups of their customers and characterize the customer group on basis
of purchasing.
• Clustering is used in the identification of groups of automobiles
Insurance policy customer.
• Clustering is used in the identification of groups of house in a city on
the basis of house type, their cost and geographical location.
• Clustering is used to classify the document on the web for information
discovery.

4.What are the requirements of cluster analysis?
The basic requirements of cluster analysis are
• Dealing with different types of attributes.
• Dealing with noisy data.
• Constraints on clustering.
• Dealing with arbitrary shapes.
• High dimensionality
• Ordering of input data
• Interpretability and usability
• Determining input parameter and
• Scalability

5.What are the different types of data used for cluster analysis?
The different types of data used for cluster analysis are interval scaled, binary,
nominal, ordinal and ratio scaled data.

6. What are interval scaled variables?
Interval scaled variables are continuous measurements of linear scale.
For example, height and weight, weather temperature or coordinates for any cluster.
These measurements can be calculated using Euclidean distance or Minkowski distance.
  
7. Define Binary variables? And what are the two types of binary variables?
Binary variables are understood by two states 0 and 1, when state is 0, variable is
absent and when state is 1, variable is present. There are two types of binary variables,
symmetric and asymmetric binary variables. Symmetric variables are those variables that
have same state values and weights. Asymmetric variables are those variables that have
not same state values and weights.

8. Define nominal, ordinal and ratio scaled variables?
A nominal variable is a generalization of the binary variable. Nominal variable
has more than two states, For example, a nominal variable, color consists of four states,
red, green, yellow, or black. In Nominal variables the total number of states is N and it is
denoted by letters, symbols or integers.
An ordinal variable also has more than two states but all these states are ordered
in a meaningful sequence.
A ratio scaled variable makes positive measurements on a non-linear scale, such
as exponential scale, using the formula
AeBt or Ae-Bt
Where A and B are constants.

9. What do u mean by partitioning method?
In partitioning method a partitioning algorithm arranges all the objects into
various partitions, where the total number of partitions is less than the total number of
objects. Here each partition represents a cluster. The two types of partitioning method are
k-means and k-medoids.

10. Define CLARA and CLARANS?
Clustering in LARge Applications is called as CLARA. The efficiency of
CLARA depends upon the size of the representative data set. CLARA does not work
properly if any representative data set from the selected representative data sets does not
find best k-medoids.
To recover this drawback a new algorithm, Clustering Large Applications based
upon RANdomized search (CLARANS) is introduced. The CLARANS works like
CLARA, the only difference between CLARA and CLARANS is the clustering process
that is done after selecting the representative data sets.

11. What is Hierarchical method?
Hierarchical method groups all the objects into a tree of clusters that are arranged
in a hierarchical order. This method works on bottom-up or top-down approaches.

12. Differentiate Agglomerative and Divisive Hierarchical Clustering?
Agglomerative Hierarchical clustering method works on the bottom-up approach.
In Agglomerative hierarchical method, each object creates its own clusters. The single
Clusters are merged to make larger clusters and the process of merging continues until all
the singular clusters are merged into one big cluster that consists of all the objects.
Divisive Hierarchical clustering method works on the top-down approach. In this
method all the objects are arranged within a big singular cluster and the large cluster is
continuously divided into smaller clusters until each cluster has a single object.

13. What is CURE?
Clustering Using Representatives is called as CURE. The clustering algorithms
generally work on spherical and similar size clusters. CURE overcomes the problem of
spherical and similar size cluster and is more robust with respect to outliers.

14. Define Chameleon method?
Chameleon is another hierarchical clustering method that uses dynamic modeling.
Chameleon is introduced to recover the drawbacks of CURE method. In this method two
clusters are merged, if the interconnectivity between two clusters is greater than the
interconnectivity between the objects within a cluster.

15. Define Density based method?
Density based method deals with arbitrary shaped clusters. In density-based
method, clusters are formed on the basis of the region where the density of the objects is
high.

16. What is a DBSCAN?
Density Based Spatial Clustering of Application Noise is called as DBSCAN.
DBSCAN is a density based clustering method that converts the high-density objects
regions into clusters with arbitrary shapes and sizes. DBSCAN defines the cluster as a
maximal set of density connected points.

17. What do you mean by Grid Based Method?
In this method objects are represented by the multi resolution grid data structure.
All the objects are quantized into a finite number of cells and the collection of cells build
the grid structure of objects. The clustering operations are performed on that grid
structure. This method is widely used because its processing time is very fast and that is
independent of number of objects.

18. What is a STING?
Statistical Information Grid is called as STING; it is a grid based multi resolution
clustering method. In STING method, all the objects are contained into rectangular cells,
these cells are kept into various levels of resolutions and these levels are arranged in a
hierarchical structure.

19. Define Wave Cluster?
It is a grid based multi resolution clustering method. In this method all the objects
are represented by a multidimensional grid structure and a wavelet transformation is
applied for finding the dense region. Each grid cell contains the information of the group
of objects that map into a cell. A wavelet transformation is a process of signaling that
produces the signal of various frequency sub bands.

20. What is Model based method?
For optimizing a fit between a given data set and a mathematical model based
methods are used. This method uses an assumption that the data are distributed by
probability distributions. There are two basic approaches in this method that are
1. Statistical Approach
2. Neural Network Approach.

21. What is the use of Regression?
Regression can be used to solve the classification problems but it can also be used
for applications such as forecasting. Regression can be performed using many different
types of techniques; in actually regression takes a set of data and fits the data to a
formula.

22. What are the reasons for not using the linear regression model to estimate the
output data?
There are many reasons for that, One is that the data do not fit a linear model, It is
possible however that the data generally do actually represent a linear model, but the
linear model generated is poor because noise or outliers exist in the data.
Noise is erroneous data and outliers are data values that are exceptions to the usual and
expected data.

23. What are the two approaches used by regression to perform classification?
Regression can be used to perform classification using the following approaches
1. Division: The data are divided into regions based on class.
2. Prediction: Formulas are generated to predict the output class value.

24. What do u mean by logistic regression?
Instead of fitting a data into a straight line logistic regression uses a logistic curve.
The formula for the univariate logistic curve is
P= e (C0+C1X1)
1+e (C0+C1X1)
The logistic curve gives a value between 0 and 1 so it can be interpreted as the
probability of class membership.

25. What is Time Series Analysis?
A time series is a set of attribute values over a period of time. Time Series
Analysis may be viewed as finding patterns in the data and predicting future values.

26. What are the various detected patterns?
Detected patterns may include:
¨ Trends : It may be viewed as systematic non-repetitive changes to the values over
time.
¨ Cycles : The observed behavior is cyclic.
¨ Seasonal : The detected patterns may be based on time of year or month or day.
¨ Outliers : To assist in pattern detection , techniques may be needed to remove or
reduce the impact of outliers.

27. What is Smoothing?
Smoothing is an approach that is used to remove the nonsystematic behaviors
found in time series. It usually takes the form of finding moving averages of attribute
values. It is used to filter out noise and outliers.

28. Give the formula for Pearson’s r
One standard formula to measure correlation is the correlation coefficient r,
sometimes called Pearson’s r. Given two time series, X and Y with means X’ and Y’,
each with n elements, the formula for r is
S (xi – X’) (yi – Y’)
(S (xi – X’)2 S(yi – Y’)2)1/2


29. What is Auto regression?
Auto regression is a method of predicting a future time series value by looking at
previous values. Given a time series X = (x1,x2,….xn) a future value, x n+1, can be found
using
x n+1 = x + j nx n + j n-1x n-1 +……+ e n+1
Here e n+1 represents a random error, at time n+1.In addition, each element in the time
series can be viewed as a combination of a random error and a linear combination of
previous values.