| Oracle® Data Mining Concepts 11g Release 2 (11.2) Part Number E12216-03 |
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| Oracle® Data Mining Concepts 11g Release 2 (11.2) Part Number E12216-03 |
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View PDF |
active learning
A feature of the support vector machine algorithm that provides a way to deal with large training data sets.
aggregation
The process of consolidating data values into a smaller number of values. For example, sales data could be collected on a daily basis and then be totalled to the week level.
algorithm
A sequence of steps for solving a problem. See data mining algorithm. The Oracle Data Mining programmatic interfaces support the following algorithms: MDL, apriori, decision tree, k-means, naive bayes, GLM, O-cluster, and support vector machine.
anomaly detection
The detection of outliers or atypical cases. To build an anomaly detection model using the Data Mining programmatic interfaces, specify classification as the mining function, SVM as the algorithm, and pass a NULL or empty string as the target column name.
apply
The data mining operation that scores data, that is, uses the model with new data to predict results.
apply settings
In the Java API, an object used to specify the kind of output desired from applying a model to data. This output may include predicted values, associated probabilities, key values, and other data.
association rules
A mining function that captures co-occurrence of items among transactions. A typical rule is an implication of the form A -> B, which means that the presence of item set A implies the presence of item set B with certain support and confidence. The support of the rule is the ratio of the number of transactions where the item sets A and B are present to the total number of transactions. The confidence of the rule is the ratio of the number of transactions where the item sets A and B are present to the number of transactions where item set A is present. Oracle Data Mining uses the Apriori algorithm for association models.
attribute
An attribute is a predictor in a predictive model or an item of descriptive information in a descriptive model. Data attributes are the columns used to build a model. Data attributes undergo transformations so that they can be used as categoricals or numericals by the model. Categoricals and numericals are model attributes. See also target.
attribute importance
A mining function providing a measure of the importance of an attribute in predicting a specified target. The measure of different attributes of a training data table enables users to select the attributes that are found to be most relevant to a mining model. A smaller set of attributes results in a faster model build; the resulting model could be more accurate. Oracle Data Mining uses the minimum description length to discover important attributes. Sometimes referred to as feature selection or key fields.
automatic data transformation
Mining models can be created in Automatic Data Preparation (ADP) mode. ADP transforms the build data according to the requirements of the algorithm, embeds the transformation instructions in the model, and uses the instructions to transform the test or scoring data when the model is applied.
build settings
In the Java API, an object that captures the high-level specifications used to build a model. Build settings must specify a mining function; they may specify an algorithm. Oracle Data Mining supports the following mining functions: classification, regression, association, attribute importance, and clustering. anomaly detection is support through the classification mining function.
case
All the data collected about a specific transaction or related set of values. A data set is a collection of cases. Cases are also called records or examples. In the simplest situation, a case corresponds to a row in a table.
case table
A table or view in single-record case format. All the data for each case is contained in a single row. The case table may include a case ID column that holds a unique identifier for each row. Mining data must be presented as a case table.
categorical attribute
An attribute whose values correspond to discrete categories. For example, state is a categorical attribute with discrete values (CA, NY, MA). Categorical attributes are either non-ordered (nominal) like state or gender, or ordered (ordinal) such as high, medium, or low temperatures.
category
In the Java interface, corresponds to a distinct value of a categorical attribute. Categories may have character or numeric values.
classification
A mining function for predicting categorical target values for new records using a model built from records with known target values. Oracle Data Mining supports the following algorithms for classification: Naive Bayes, Decision Tree, and Support Vector Machines.
cluster centroid
The vector that encodes, for each attribute, either the mean (if the attribute is numerical) or the mode (if the attribute is categorical) of the cases in the training data assigned to a cluster. A cluster centroid is often referred to as "the centroid."
clustering
A mining function for finding naturally occurring groupings in data. More precisely, given a set of data points, each having a set of attributes, and a similarity measure among them, clustering is the process of grouping the data points into different clusters such that data points in the same cluster are more similar to one another and data points in different clusters are less similar to one another. Oracle Data Mining supports two algorithms for clustering,k-means and orthogonal partitioning clustering.
confusion matrix
Measures the correctness of predictions made by a model from a test task. The row indexes of a confusion matrix correspond to actual values observed and provided in the test data. The column indexes correspond to predicted values produced by applying the model to the test data. For any pair of actual/predicted indexes, the value indicates the number of records classified in that pairing.
When predicted value equals actual value, the model produces correct predictions. All other entries indicate errors.
connection
In the Java API, an object used to connect to the data mining server in an Oracle database to perform data mining tasks.
cost matrix
An n by n table that defines the cost associated with a prediction versus the actual value. A cost matrix is typically used in classification models, where n is the number of distinct values in the target, and the columns and rows are labeled with target values. The rows are the actual values; the columns are the predicted values.
counterexample
Negative instance of a target. Counterexamples are required for classification models, except for one-class support vector machines.
data mining
The process of discovering hidden, previously unknown, and usable information from a large amount of data. This information is represented in a compact form, often referred to as a model.
data mining algorithm
A specific technique or procedure for producing a data mining model. An algorithm uses a specific model representation and may support one or more mining functions.
The algorithms in the Oracle Data Mining programming interfaces are naive bayes, support vector machine, generalized linear model, and decision tree for classification; support vector machine and generalized linear model for regression; k-means and O-cluster for clustering; minimum description length for attribute importance; non-negative matrix factorization for feature extraction; apriori for associations, and one-class support vector machine for anomaly detection.
data mining server
The component of the Oracle database that implements the data mining engine and persistent metadata repository. You must connect to a data mining server before performing data mining tasks. The data mining server is the Oracle Data Mining implementation of the Data Mining Engine (DME) in the Java API.
descriptive model
A descriptive model helps in understanding underlying processes or behavior. For example, an association model describes consumer behavior. See also mining model.
discretization
Discretization groups related values together under a single value (or bin). This reduces the number of distinct values in a column. Fewer bins result in models that build faster. Many Oracle Data Mining algorithms (for example NB) may benefit from input data that is discretized prior to model building, testing, computing lift, and applying (scoring). Different algorithms may require different types of binning. Oracle Data Mining includes transformations that perform top N frequency binning for categorical attributes and equi-width binning and quantile binning for numerical attributes.
distance-based (clustering algorithm)
Distance-based algorithms rely on a distance metric (function) to measure the similarity between data points. Data points are assigned to the nearest cluster according to the distance metric used.
decision tree
A decision tree is a representation of a classification system or supervised model. The tree is structured as a sequence of questions; the answers to the questions trace a path down the tree to a leaf, which yields the prediction.
Decision trees are a way of representing a series of questions that lead to a class or value. The top node of a decision tree is called the root node; terminal nodes are called leaf nodes. Decision trees are grown through an iterative splitting of data into discrete groups, where the goal is to maximize the distance between groups at each split.
An important characteristic of the decision tree models is that they are transparent; that is, there are rules that explain the classification.
See also rule.
equi-width binning
Equi-width binning determines bins for numerical attributes by dividing the range of values into a specified number of bins of equal size.
explode
For a categorical attribute, replace a multi-value categorical column with several binary categorical columns. To explode the attribute, create a new binary column for each distinct value that the attribute takes on. In the new columns, 1 indicates that the value of the attribute takes on the value of the column; 0, that it does not. For example, suppose that a categorical attribute takes on the values {1, 2, 3}. To explode this attribute, create three new columns, col_1, col_2, and col_3. If the attribute takes on the value 1, the value in col_1 is 1; the values in the other two columns is 0.
feature
A combination of attributes in the data that is of special interest and that captures important characteristics of the data. See feature extraction.
See also text feature.
feature extraction
Creates a new set of features by decomposing the original data. Feature extraction lets you describe the data with a number of features that is usually far smaller than the number of original attributes. See also non-negative matrix factorization.
generalized linear model
A statistical technique for linear modeling. Generalized linear models (GLM) include and extend the class of simple linear models. Oracle Data Mining supports logistic regression for GLM classification and linear regression for GLM regression.
Java Data Mining
A Pure Java API that facilitates development of data mining-enabled applications. Java Data Mining (JDM) supports common data mining operations, as well as the creation, persistence, access, and maintenance of metadata supporting mining activities. JDM is described in the Java Community Process Specification JSR-73. The Java interface to Oracle Data Mining is an extension of JDM.
k-means
A distance-based clustering algorithm that partitions the data into a predetermined number of clusters (provided there are enough distinct cases). Distance-based algorithms rely on a distance metric (function) to measure the similarity between data points. Data points are assigned to the nearest cluster according to the distance metric used. Oracle Data Mining provides an enhanced version of k-means.
lift
A measure of how much better prediction results are using a model than could be obtained by chance. For example, suppose that 2% of the customers mailed a catalog make a purchase; suppose also that when you use a model to select catalog recipients, 10% make a purchase. Then the lift for the model is 10/2 or 5. Lift may also be used as a measure to compare different data mining models. Since lift is computed using a data table with actual outcomes, lift compares how well a model performs with respect to this data on predicted outcomes. Lift indicates how well the model improved the predictions over a random selection given actual results. Lift allows a user to infer how a model will perform on new data.
lineage
The sequence of transformations performed on a data set during the data preparation phase of the model build process.
min-max normalization
Normalize each attribute using the transformation x_new = (x_old-min)/ (max-min).
minimum description length
Given a sample of data and an effective enumeration of the appropriate alternative theories to explain the data, the best theory is the one that minimizes the sum of
The length, in bits, of the description of the theory
The length, in bits, of the data when encoded with the help of the theory
This principle is used to select the attributes that most influence target value discrimination in attribute importance.
mining function
A major subdomain of data mining that shares common high level characteristics. The Oracle Data Mining programming interfaces support the following mining functions: classification, regression, attribute importance, feature extraction, and clustering. In both programming interfaces, anomaly detection is supported as classification.
mining model
An important function of data mining is the production of a model. A model can be a supervised model or an unsupervised model. Technically, a mining model is the result of building a model from mining settings. The representation of the model is specific to the algorithm specified by the user or selected by the DMS. A model can be used for direct inspection, for example, to examine the rules produced from an association model, or to score data.
mining result
The end product(s) of a mining task. For example, a build task produces a mining model; a test task produces a test result.
missing value
A data value that is missing because it was not measured (that is, has a null value), not answered, was unknown, or was lost. Data mining algorithms vary in the way they treat missing values. There are several typical ways to treat them: ignore then, omit any records containing missing values, replace missing values with the mode or mean, or infer missing values from existing values.
model
In the Java API, the object resulting from the application of an algorithm to data, as specified in a build settings object. See also mining model.
multi-record case
Each case in the data is stored as multiple records in a table with columns sequenceID, attribute_name, and value. Also known as transactional format. See also single-record case.
naive bayes
An algorithm for classification that is based on Bayes's theorem. Naive Bayes makes the assumption that each attribute is conditionally independent of the others: given a particular value of the target, the distribution of each predictor is independent of the other predictors.
nested table
An unordered set of data elements, all of the same data type. It has a single column, and the type of that column is a built-in type or an object type. If an object type, the table can also be viewed as a multicolumn table, with a column for each attribute of the object type. Nested tables can contain other nested tables.
non-negative matrix factorization
A feature extraction algorithm that decomposes multivariate data by creating a user-defined number of features, which results in a reduced representation of the original data.
normalization
Normalization consists of transforming numerical values into a specific range, such as [–1.0,1.0] or [0.0,1.0] such that x_new = (x_old-shift)/scale. Normalization applies only to numerical attributes. Oracle Data Mining provides transformations that perform min-max normalization, scale normalization, and z-score normalization.
numerical attribute
An attribute whose values are numbers. The numeric value can be either an integer or a real number. Numerical attribute values can be manipulated as continuous values. See also categorical attribute.
one-class support vector machine
The version of the support vector machine model used to solve anomaly detection problems. The Oracle Data Mining programmatic interfaces implement the one-class algorithm as classification.
orthogonal partitioning clustering
An Oracle proprietary clustering algorithm that creates a hierarchical grid-based clustering model, that is, it creates axis-parallel (orthogonal) partitions in the input attribute space. The algorithm operates recursively. The resulting hierarchical structure represents an irregular grid that tessellates the attribute space into clusters.
outlier
A data value that does not come from the typical population of data; in other words, extreme values. In a normal distribution, outliers are typically at least 3 standard deviations from the mean.
physical data set
In the Java API, an object that identifies data to be used as input to data mining. The data referenced by a physical data set object can be used in model build, model apply (scoring), lift computation, statistical analysis, and similar operations. The physical data specification includes information about the format of the data and the roles that the data columns play. In the Oracle Data Mining Java interface, the physical data set must be a table or view within the database instance specified in the connection object.
positive target value
In binary classification problems, you may designate one of the two classes (target values) as positive, the other as negative. When Oracle Data Mining computes a model's lift, it calculates the density of positive target values among a set of test instances for which the model predicts positive values with a given degree of confidence.
predictive model
A predictive model is an equation or set of rules that makes it possible to predict an unseen or unmeasured value (the dependent variable or output) from other, known values (independent variables or input). The form of the equation or rules is suggested by mining data collected from the process under study. Some training or estimation technique is used to estimate the parameters of the equation or rules. A predictive model is a supervised model.
prepared data
Data that is suitable for model building using a specified algorithm. Data preparation often accounts for much of the time spent in a data mining project. Oracle Data Mining includes transformations to perform common data preparation functions (binning, normalization, and so on)
prior probabilities
The set of prior probabilities specifies the distribution of examples of the various classes in the original source data. Also referred to as priors, these could be different from the distribution observed in the data set provided for model build.
quantile binning
A numerical attribute is divided into bins such that each bin contains approximately the same number of cases.
random sample
A sample in which every element of the data set has an equal chance of being selected.
recode
Literally "change or rearrange the code." Recoding can be useful in many instances in data mining. Here are some examples:
Missing values treatment: Missing values may be indicated by something other than NULL, such as "0000" or "9999" or "NA" or some other string. One way to treat the missing value is to recode, for example, "0000" to NULL. Then the Oracle Data Mining algorithms and the database recognize the value as missing.
Change data type of variable: For example, change "Y" or "Yes" to 1 and "N" or "No" to 0.
Establish a cutoff value: For example, recode all incomes less than $20,000 to the same value.
Group items: For example, group individual US states into regions. The "New England region" might consist of ME, VT, NH, MA, CT, and RI; to implement this, recode the five states to, say, NE (for New England).
regression
A data mining function for predicting continuous target values for new records using a model built from records with known target values. Oracle Data Mining provides the Support Vector Machine algorithm for regression.
rule
An expression of the general form if X, then Y. An output of certain algorithms, such as clustering, association, and decision tree. The predicate X may be a compound predicate.
scale normalization
Normalize each attribute using the transformation x_new = (x-0)/ max(abs(max), abs(min)).
schema
Database schema, that is, a collection of database objects, including logical structures such as tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database links.
single-record case
Each case in the data is stored as one record (row) in a table. Contrast with multi-record case.
sparse data
Data for which only a small fraction of the attributes are nonzero or non-null in any given case. Market basket data and text mining data are often sparse.
split
Divide a data set into several disjoint subsets. For example, in a classification problem, a data set is often divided in to a training data set and a test data set.
stratified sample
Divide the data set into disjoint subsets (strata) and then take a random sample from each of the subsets. This technique is used when the distribution of target values is skewed greatly. For example, response to a marketing campaign may have a positive target value 1% of the time or less. A stratified sample provides the data mining algorithms with enough positive examples to learn the factors that differentiate positive from negative target values. See also random sample.
supermodel
Mining models that contain instructions for their own data preparation. Oracle Data Mining provides Automatic Data Transformation (ADP) and embedded data transformation, which together provide support for supermodels.
supervised model
A data mining model that is built using a known dependent variable, also referred to as the target. Classification and regression techniques are examples of supervised mining. See unsupervised model. Also referred to as predictive model.
support vector machine
An algorithm that uses machine learning theory to maximize predictive accuracy while automatically avoiding over-fit to the data. Support vector machines can make predictions with sparse data, that is, in domains that have a large number of predictor columns and relatively few rows, as is the case with bioinformatics data. Support vector machine can be used for classification, regression, and anomaly detection.
table
The basic unit of data storage in an Oracle database. Table data is stored in rows and columns.
target
In supervised learning, the identified attribute that is to be predicted. Sometimes called target value or target attribute. See also attribute.
test metrics
In the Java API, an object results from the testing of a supervised model with test data. The test metrics computed depend on the mining function. For classification, the accuracy, confusion-matrix, lift, and receiver-operating characteristics can be computed to access the model. Similarly for regression, R-squared and RMS errors can be computed. Test metrics can also be computed using the PL/SQL interface.
task
In the Java API, an object that represents all the information needed to perform a mining operation, such as build, test, apply, import, and export. A task is executed using the execute method of a connection object.
text feature
A combination of words that captures important attributes of a document or class of documents. Text features are usually keywords, frequencies of words, or other document-derived features. A document typically contains a large number of words and a much smaller number of features.
text mining
Conventional data mining done using text features. Text features are usually keywords, frequencies of words, or other document-derived features. Once you derive text features, you mine them just as you would any other data. Both Oracle Data Mining and Oracle Text support text mining.
top N frequency binning
This type of binning bins categorical attributes. The bin definition for each attribute is computed based on the occurrence frequency of values that are computed from the data. The user specifies a particular number of bins, say N. Each of the bins bin_1,..., bin_N corresponds to the values with top frequencies. The bin bin_N+1 corresponds to all remaining values.
transactional format
Each case in the data is stored as multiple records in a table with columns sequenceID, attribute_name, and value. Also known as multi-record case. Compare with single-record case.
transformation
A function applied to data resulting in a new representation of the data. For example, discretization and normalization are transformations on data.
trimming
A technique used for dealing with outliers. Trimming removes values in the tails of a distribution in the sense that trimmed values are ignored in further computations. This is achieved by setting the tails to NULL.
unstructured data
Images, audio, video, geospatial mapping data, and documents or text data are collectively known as unstructured data. Oracle Data Mining supports the mining of unstructured text data.
unsupervised model
A data mining model built without the guidance (supervision) of a known, correct result. In supervised learning, this correct result is provided in the target attribute. Unsupervised learning has no such target attribute. Clustering and association are examples of unsupervised mining functions. See supervised model.
view
A view takes the output of a query and treats it as a table. Therefore, a view can be thought of as a stored query or a virtual table. You can use views in most places where a table can be used.
winsorizing
A way of dealing with outliers. Winsorizing involves setting the tail values of an particular attribute to some specified value. For example, for a 90% Winsorization, the bottom 5% of values are set equal to the minimum value in the 6th percentile, while the upper 5% are set equal to the maximum value in the 95th percentile.
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