Introduction: It works by grouping data objects into a tree of clusters. It creates a hierarchical decomposition of the given set of data objects. Instead, a series of partitions takes place, which may run from a single cluster containing all objects to n clusters each containing a single object. There are two basic methods of hierarchical alg.: 1) Agglomerative 2) Divisive Agglomerative or Bottom up strategy : Starts with the points as individual clusters. At each step, merge the closest pair of clusters until only one cluster. i.e., begins with as many clusters as objects. Clusters are successively merged until only one cluster remains.
give that in simple terms
Hierarchical clustering is a method of grouping data points into a tree-like structure of clusters. It creates a hierarchy of the given set of data objects by repeatedly merging the closest pair of clusters until only one cluster. There are two main methods of hierarchical clustering - agglomerative and divisive.
In agglomerative clustering, also known as the bottom-up approach, we start with each data point as an individual cluster. Then, at each step, we merge the two closest clusters together until only one cluster is left. This process continues until all data points belong to the same cluster.
Proximity Matrix: It is used in Agglomerative means, which possible obj. can be merge together
The proximity matrix is used in agglomerative hierarchical clustering to determine which objects or data points can be merged together at each step of the clustering process based on their distances or similarities.
Dendrogram: A tree structure called dendrogram is commonly used to represent the process of hierarchical clustering. To improve the quality of hierarchical clustering:
Perform careful analysis of object “linkages” at each hierarchical partitioning.
Integrate hierarchical agglomeration & other approaches by first using agglomerative alg. to group objects into microclusters. Then performing macro on to the micro clusters using another clustering methods are: e.g: CURE BIRCH CHAMELEON Note: Cluster quality is poor because of inadjustability i.e, once the decision made it won’t return it will go continuous.
The dendrogram, a tree-like structure, is commonly used to illustrate the process of hierarchical clustering. To improve the quality of hierarchical clustering, it is important to carefully analyze the linkages between objects at each stage of the partitioning.
An approach to enhancing hierarchical clustering involves integrating agglomerative clustering with other methods. This be achieved by initially using the agglomerative algorithm to group objects into microclusters, followed by applying other clustering methods to these microclusters. Examples of methods include CURE, BIRCH, and CHAMELEON.
It's worth noting that the cluster quality may due to the inability to adjust the decision once it's made leading to a continuous process without the ability to revise previous steps.
CURE:(Clustering Using Representatives) Creates cluster by sampling the database & shrinks them toward the center of the cluster by a specified fraction.
CURE fails when clustering categorical data.
It ignores aggregate interconnectivity of objects in separate clusters.
CURE follows the cluster proximity.
Taking a sample from a dataset & shrinking it until we get a exact good cluster. This follows the similarity, there is no interconnectivity.
BIRCH:Balanced Iterative Reducing & Clustering using Hierarchies. BIRCH is designed for clustering a large amount of numerical data by integration of hierarchical clustering & other clustering methods such as iterative partitioning. BIRCH overcomes the two difficulties of Agglomerative clustering – 1) Scalability 2) Inability to undo what was done in the previous step.
BIRCH Two Concepts:
Clustering Feature(CF): It is a 3 dimensional vector summarizing information about cluster of objects.
CF = (n , Ls, Ss)
Where n= no of points in the cluster
Ls = linear sum of the n points
Ss = Square sum of the data points.
CF Tree:
It is a height balance tree that stores the clustering features for a hierarchical clustering.
- A non leaf node in a tree has decendents or “Children”
- The non leaf nodes stores sum of the CF’s of their
children.
CF tree has two parameters:
2)Threashold: Maximum diameter of sub-cluster stored at the leaf nodes, of the tree.
Drawback: Handles only numeric data & sensitive to the order of the data record.
Advantage: BIRCH will efficiently cluster even the dynamic data set & CF Tree is very useful for this.
CURE (Clustering Using Representatives) is a clustering algorithm that creates clusters by sampling the and then gradually bringing the sampled points towards the center of the cluster by a specified fraction. However, it does not perform well when clustering categorical data and overlooks the interconnectedness of objects in separate clusters. CURE primarily focuses cluster proximity and similarity but does not consider interconnectivity.
On the other hand, BIRCH (Balanced Iter Reducing and Clustering using Hierarchies) is specifically designed for clustering large amounts of numerical data by integrating hierarchical clustering with other methods such as iterative partition. BIRCH addresses two major challenges of agglomerative - scalability and the inability to undo previous steps. BIRCH is based on two main concepts:
1.ustering Feature (CF): This is a three-dimensional vector that summarizes information about a cluster of objects, consisting of the number of points in the cluster (n), the linear sum of the n points (Ls), and the square sum of the data points (S).
The CF tree is governed by:
Although BIRCH efficiently clusters dynamic datasets and the CF Tree is beneficial for this purpose, it has drawbacks such as handling only numeric data and being sensitive to the order of the data records.
CHAMELEON: A hierarchical clustering alg. Using dynamic modeling. This derived based on the observed weakness of two hierarchical clustering alg.’s - ROCK& CURE Chameleon uses a k-nearest neighbor graph approach. Chameleon uses a graph partitioning alg. to partition the k-nearest graph into a large no. of relatively small subclusters. It then uses an agglomerative hierarchical clustering alg. that repeatedly merges subclusters based on their similarity. To determine the pairs of most similar subclusters, it takes into account both the interconnectivity as well as the closeness of the clusters
Explain this in simple words
Chameleon is a hierarchical clustering algorithm that addresses the limitations of hierarchical clustering algorithms such as ROCK and CURE. It does this by using a dynamic modeling approach and a k-nearest neighbor graph.
First, Chameleon creates a karest neighbor graph to represent the relationships between data points. Then, it partitions this graph into many relatively small subclusters using a graph partitioning algorithm.
After that, it uses an agglomerative hierarchical clustering algorithm to merge these subclusters based on their similarity. Chameleon considers both the interconnectedness and the proximity of the clusters to determine which pairs of subclusters are the most similar. This holistic approach helps Chameleon to create more accurate and useful clusters.
Here we will have a imaginative model for each cluster & find the best fit of data to given model. It locates the cluster in the spatial area with the help of density function. Since we have a standard mathematical model already will know the no. of clusters that must be present in the data set. Eg:- *EM, *Conceptual clustering, *Neural Networks approach. EM-(Expectation Maximization) : Here each cluster is represented by a distribution. The entire data set is a mixture of these distribution. Each individual distribution is termed as component distribution. So, we can cluster the data by looking for distribution. EM is an extension of k-means alg.
It appears that you are describing a process for creating an imaginative for each cluster and identifying the best fit of data to a given model. This involves locating the cluster in the spatial area using a density to understand the structure of the data. Some methods that follow this approach include Expectation Maximization (EM), conceptual clustering, and the neural networks approach.
Expectation Maximization (EM) focuses on representing each cluster with a distribution. The entire dataset is seen as a mixture of these distributions, with each individual distribution to as a component distribution. By identifying these distributions, EM algorithm can effectively cluster the data. It is worth that EM is an extension of the k-means algorithm, providing a more nuanced method for discovering clusters within dataset.
what is rule based classification in data mining
Rule-based classification in data mining involves the creation of classification rules that specify the criteria assigning a data instance to a particular class or category. These rules are derived from the patterns and discovered in the dataset. Each rule typically consists of a set of conditions or attributes that, when satisfied by a data instance, determine its classification.
Rule-based classifiers are particularly useful in decision-making processes due to their interpretability and transparency. These classification rules are often derived using techniques such as decision trees, association rule mining, and expert knowledge elicitation. When applied to new data, these rules enable the automated categorization of data instances into predefined classes based on their attributes or characteristics.
If more than one rule are triggered, need conflict resolution Size ordering: assign the highest priority to the triggering rules that has the “toughest” requirement (i.e., with the most attribute tests) Class-based ordering: decreasing order of prevalence or misclassification cost per class Rule-based ordering (decision list): rules are organized into one long priority list, according to some measure of rule quality or by experts Explain this in short term
In rule-based classification, when multiple rules are triggered for a data instance, resolution is needed. This can be achieved through:
is techniques and methods meaning are same
Yes, in general usage, the terms "techniques" and "methods" often used interchangeably and can convey a similar meaning. Both to approaches, processes, or procedures used to achieve a particular goal in a specific field or context. While there may be subtle differences in certain contexts, they are commonly used synonymously.
Model based clustering Here we will have a imaginative model for each cluster & find the best fit of data to given model. It locates the cluster in the spatial area with the help of density function. Since we have a standard mathematical model already will know the no. of clusters that must be present in the data set. Eg:- *EM, *Conceptual clustering, *Neural Networks approach. EM-(Expectation Maximization) : Here each cluster is represented by a distribution. The entire data set is a mixture of these distribution. Each individual distribution is termed as component distribution. So, we can cluster the data by looking for distribution. EM is an extension of k-means alg.
Explain this in simple words
In model-based clustering, we create an imaginary model for each cluster and then find the best fit of data to these models. This method a density function to locate clusters in the data's spatial area. Because we have a standard mathematical model, we can determine the number of clusters present in the data set.
For example, the Expectation Maximization (EM) approach represents each cluster as a distribution. The entire is seen as a combination of these distributions, where each individual distribution is called a component distribution. By identifying these distributions, can effectively cluster the data. EM is an advanced version of the k-means algorithm, providing a more sophisticated way to discover clusters within a dataset.
The Expectation-Maximization (EM) algorithm is an iterative optimization method that combines different unsupervised machine learning algorithms to find maximum likelihood or maximum posterior estimates of parameters in statistical models that involve unobserved latent variables. The EM algorithm is commonly used for latent variable models and can handle missing data. It consists of an estimation step (E-step) and a maximization step (M-step), forming an iterative process to improve model fit.
In the E step, the algorithm computes the latent variables i.e. expectation of the log-likelihood using the current parameter estimates. In the M step, the algorithm determines the parameters that maximize the expected log-likelihood obtained in the E step, and corresponding model parameters are updated based on the estimated latent variables.
Explain this in simple words?
The Expectation-Maximization (EM) algorithm is a technique used in machine learning to find the best estimates of parameters in statistical models where some information is not directly observable. It is commonly used when dealing with incomplete data or when there are variables that cannot be directly measured.
The algorithm works by iteratively improving its estimates of the model's parameters. In the first step, it calculates the expected values of the unobserved variables based on its current parameter estimates. Then, in the second step, it updates the parameters to maximize the likelihood based on the expected values calculated in the previous step. This process is repeated until the algorithm converges on the best possible parameter estimates for the given data.
applications of data mining 2 marks
Two common applications of data mining are:
Marketing: Data mining is used to analyze customer behavior, preferences, and purchasing patterns to improve targeted marketing efforts and customer retention strategies.
Healthcare: In healthcare, data mining is applied to analyze patient records, identify patterns in disease diagnosis and treatment outcomes, and improve decision-making processes for personalized patient care.
Often there exists data obj’s. that do not agree with any general behavior or model of the data set.
Such obj’s. are different or inconsistent with the remaining obj. are called outliers.
Outliers are mainly caused by execution error.
Many mining alg. focus on minimizing the outliers but this would result in a loss of imp. info.
Outlier detection & analysis is an interesting task in data mining & referred as outlier mining.
Many applications: Fraud detection , * prioritizing customer & * Medical analysis.
Two subproblems:
Now lets try using data visualization method for outlier detection. This seems more effective because human eyes are very fast and effective in noticing data inconsistency. But this is weak in data with categorical attri. Or in high dim. Since human can be visualize only in 2D & 3D.
Four approaches
Working Hypothesis:
Alternative Hypothesis:
(There are different kinds of alternative dist.) a) Inherent alternative distribution. b) Mixture alternative distribution. c) Slippage alternative distribution.
There are two basic types of procedures for detecting outliers. - Block procedures - Consecutive (or sequential) procedures. 2) Distance based approaches: This concept assigns numeric distance to data objects and computes outliers as data objects with relatively larger distances.
Algorithms: * Indexed_ Base algorithm – it uses multidimensional indexing structure
* Cell – Based Algorithm –
it was developed for memory resident data sets. 3) Density – Based local Outliers Detection: or Depth_Based Technique: LOF - Degree High - outliers. Degree Low - Not outlier. LOF-Local outlier factor LOF = avg( reachability distance / min pts.)
Two techniques are:
Explain this in simple and understandable words?
Outliers in data are observations that significantly differ from the general pattern or model of the dataset. These outliers are often caused by errors in data collection or measurement. While many data mining algorithms aim to minimize the impact of outliers, neglecting them may result in the loss of important information. Therefore, outlier detection and analysis, referred to as outlier mining, are crucial tasks in data mining.
This process is essential in various applications such as fraud detection, customer prioritization, and medical analysis. Outlier mining involves defining what data can be considered inconsistent and finding efficient methods to identify these outliers.
One effective method for outlier detection is data visualization, as human eyes are adept at recognizing data inconsistencies. However, this approach has limitations in datasets with categorical attributes or high dimensions, as human visualization is typically limited to 2D or 3D representations.
Several approaches are used for outlier detection, including statistical distribution-based methods, distance-based approaches, density-based local outlier detection, and deviation-based outliers detection. These approaches utilize different statistical and computational techniques to identify outliers in the data. For example, distance-based approaches assign numerical distances to data objects and identify outliers with relatively larger distances, while density-based techniques assess the local density of data points to determine outlier status. Each approach has its unique strengths and can be suitable for different types of datasets.
) Distance based approaches: This concept assigns numeric distance to data objects and computes outliers as data objects with relatively larger distances.
Algorithms: * Indexed_ Base algorithm – it uses multidimensional indexing structure
* Cell – Based Algorithm –
it was developed for memory resident data sets.
Distance-based approaches in outlier detection utilize the concept of assigning numerical distances to data objects and identifying outliers as objects with comparatively larger distances. Two specific algorithms used in this approach are the Indexed Base algorithm and the Cell-Based Algorithm.
The Indexed Base algorithm employs a multidimensional indexing structure to efficiently calculate numeric distances and detect outliers. On the other hand, the Cell-Based Algorithm was specifically developed for memory resident data sets, utilizing techniques tailored such datasets to effectively identify outliers based on their distances from other data objects.
INTRODUCTION: ETL stands for Extract, Transform, Load and it is a process used in data warehousing to extract data from various sources, transform it into a format suitable for loading into a data warehouse, and then load it into the warehouse. The process of ETL can be broken down into the following three stages: Extract: The first stage in the ETL process is to extract data from various sources such as transactional systems, spreadsheets, and flat files. This step involves reading data from the source systems and storing it in a staging area. Transform: In this stage, the extracted data is transformed into a format that is suitable for loading into the data warehouse. This may involve cleaning and validating the data, converting data types, combining data from multiple sources, and creating new data fields. Load: After the data is transformed, it is loaded into the data warehouse. This step involves creating the physical data structures and loading the data into the warehouse. The ETL process is an iterative process that is repeated as new data is added to the warehouse. The process is important because it ensures that the data in the data warehouse is accurate, complete, and up-to-date. It also helps to ensure that the data is in the format required for data mining and reporting. Additionally, there are many different ETL tools and technologies available, such as Informatica, Talend, DataStage, and others, that can automate and simplify the ETL process.
ETL is a process in Data Warehousing and it stands for Extract, Transform and Load. It is a process in which an ETL tool extracts the data from various data source systems, transforms it in the staging area, and then finally, loads it into the Data Warehouse system.
Explain this in simple terms
In simple terms, ETL (Extract, Transform, Load) is a process used in data warehousing to handle the flow of data. First, it extracts data from different sources like databases, spreadsheets, or files. Then, it transforms the data to make it suitable for the data warehouse by cleaning it, converting types, and combining information. Finally, it loads the transformed data into the data warehouse for analysis and reporting. This process is crucial for ensuring that the data is accurate, complete, and in the right format for analysis. ETL tools like Informatica, Talend, and DataStage help automate and simplify these tasks.
Metadata is data that describes and contextualizes other data. It provides information about the content, format, structure, and other characteristics of data, and can be used to improve the organization, discoverability, and accessibility of data.
Metadata can be stored in various forms, such as text, XML, or RDF, and can be organized using metadata standards and schemas. There are many metadata standards that have been developed to facilitate the creation and management of metadata, such as Dublin Core, schema.org, and the Metadata Encoding and Transmission Standard (METS). Metadata schemas define the structure and format of metadata and provide a consistent framework for organizing and describing data.
Metadata can be used in a variety of contexts, such as libraries, museums, archives, and online platforms. It can be used to improve the discoverability and ranking of content in search engines and to provide context and additional information about search results. Metadata can also support data governance by providing information about the ownership, use, and access controls of data, and can facilitate interoperability by providing information about the content, format, and structure of data, and by enabling the exchange of data between different systems and applications. Metadata can also support data preservation by providing information about the context, provenance, and preservation needs of data, and can support data visualization by providing information about the data’s structure and content, and by enabling the creation of interactive and customizable visualizations.
Explain in understndanble words and simple terms
In simple terms, metadata is like a label or description for other information. It tells us about the content, format, and structure of data, helping to organize, find, and understand it better. For example, if think of a library book, the metadata would include details such as the title, author, and genre. This information makes it easier to locate and categorize the book. Similarly, in the digital world, metadata provides context and details about data, making it easier to search, use, and share. This can be helpful in various areas like libraries, museums, online platforms, and even in ensuring data security and preservation. Metadata standards and schemas help ensure that information is structured and organized consistently, making it easier to use across different systems and applications.
Suppose that a data warehouse consists of the three dimensions time, doctor, and (7) patient, and the two measures count and charge, where charge is the fee that a doctor charges a patient for a visit. (i) Draw a schema diagram for the above data warehouse using any one of the schema classes. (ii) Starting with the base cuboid [day, doctor, patient], what specific oLAp operations should be performed in order to list the total fee collected by each doctor in2004? (iii) To obtain the same list, write an SQL query assuming the data are stored in a relational database with the schema fee (day, month, year, doctor, hospital, patient, count, charge)
Give the correct answer or diagram for it
Since the document provided is in PDF form and may not be accessible in its current state, I will provide you with the information based on the description you have given.
i) Schema Diagram: A schema diagram for the given data warehouse with the dimensions time, doctor, and patient, and the measures count and charge, might look like this:
+-------------------+ | Time | |-------------------| | - day | | - month | | - year | +-------------------+ / \ / \ / \ +------------------+ +------------------+ | Doctor | | Patient | |------------------| |------------------| | - doctor_id | | - patient_id | | - name | | - name | +------------------+ +------------------+ \ / \ / +-------+ | Fact | |-------| | - count | | - charge | +-------+
ii) OLAP Operations: The OLAP operation to list the total fee collected by each doctor in 2004 would involve performing a roll-up operation on the time dimension to aggregate the charges for each doctor over the year 2004.
iii) SQL Query: Assuming the data is stored in a relational database with the schema fee (day, month, year, doctor, hospital, patient, count, charge), a SQL query to obtain the list of total fee collected by each doctor in 2004 might look something like this:
SELECT doctor, SUM(charge) AS total_fee FROM fee WHERE year = 2004 GROUP BY doctor;
This query selects the doctor and calculates the total fee by summing the charges, for the year 2004, grouping the results by doctor.
Please note that the actual SQL query may need to be adjusted based on the specifics of the database schema and the SQL dialect being used.
jayanandkamble.files.wordpress.com
434it.files.wordpress.com
shikhadeep.com.np