ata mining is an iterative process that typically involves the following phases: a) Problem definition : A data mining project starts with the understanding of the business problem. Data mining experts, business experts, and domain experts work closely together to define the project objectives and the requirements from a business perspective. The project objective is then translated into a data mining problem definition. In the problem definition phase, data mining tools are not yet required. b) Data exploration : Domain experts understand the meaning of the metadata. They collect, describe, and explore the data. They also identify quality problems of the data. A frequent exchange with the data mining experts and the business experts from the problem definition phase is vital.
In the data exploration phase, traditional data analysis tools, for example, statistics, are used to explore the data. c) Data preparation : Domain experts build the data model for the modeling process. They collect, cleanse, and format the data because some of the mining functions accept data only in a certain format. They also create new derived attributes, for example, an average value. In the data preparation phase, data is tweaked multiple times in no prescribed order. Preparing the data for the modeling tool by selecting tables, records, and attributes, are typical tasks in this phase. The meaning of the data is not changed. Raw Data: Raw data is a term for data collected on source which has not been subjected to processing or any other manipulation. (Primary data), it is also known as primary data. It is a relative term (see data). Raw data can be input to a computer program or used in manual analysis procedures such as gathering statistics from a survey. It can refer to the binary data on D electronic storage devices such as hard disk drives (also referred to as low-level data). Suppose that the data for a feature v are in a range between 150 and 250. Then, the previous method of normalization will give all normalized data between .15 and .25; but it will accumulate the values on a small subinterval of the entire range. To obtain better distribution of values on a whole, normalized interval, e.g., [0, 1], we can use the min-max formula
VI '=(VI-Min(VI))/(Max(VI)-Min(VI)) d) Standard Deviation Normalization
Normalization by standard deviation often works well with distance measures, but transforms the data into a form unrecognizable from the original data.
VI '=(VI-Mean(V))/Std(V)
# Types of Data
Categorical Data: Categorical data (or variable) consists of names representing categories. For example, the gender (categories of male & female) of the people where you work or go to school; or the make of cars in the parking lot (categories of Ford, GM, Toyota, Mazda, KIA, etc) is categorical data.
Numerical Data: Numerical data (or variable) consists of numbers that represent counts or measurements. For example, the number of males & females where you work or go to school; or the number of the make of cars Ford, GM, Toyota, Mazda, KIA, etc is numerical data.
Dummy Variable: A dummy variable is a numerical variable used in regression analysis to represent subgroups of the sample in your study.
Discrete Variable: Discrete Variable are also called Qualitative Variable. It is nominal or ordinal.
Continuous Variable: Continuous variable are measured using interval scale or ratio scale.
Means reducing the number of cases or variables in a data matrix. The basic operations in a data-reduction process are delete column, delete a row, and reduce the number of values in a column. These operations attempt to preserve the character of the original data by deleting data that are nonessential. There are other operations that reduce dimensions, but the new data are unrecognizable when compared to the original data set, and these operations are mentioned here just briefly because they are highly applicationdependent.
# a) Entropy
A method for unsupervised feature selection or ranking based on entropy measure is a relatively simple technique; but with a large number of features its complexity increases significantly.
The similarity measure between two samples can be defined as D is the average distance among samples in the data set. Hence, is determined by the data. But, in a successfully implemented practical application, it was used a constant value of = 0.5. Normalized Euclidean distance measure is used to calculate the distance Dij between two samples xi and xj:
where n is the number of dimensions and max(k) and min(k) are maximum and minimum values used for normalization of the k-th dimension. All features are not numeric. The similarity for nominal variables is measured directly using Hamming distance.
where The total number of variables is equal to n. For mixed data, we can discretize numeric values (Binning) and transform numeric features into nominal features before we apply this similarity measure.
If the two measures are close, then the reduced set of features will satisfactorily approximate the original set. For a data set of N samples, the entropy measure is where Sij is the similarity between samples xi and xj. This measure is computed in each of the iterations as a basis for deciding the ranking of features. We rank features by gradually removing the least important feature in maintaining the order in the
# March
Where Dij is the distance between the two samples xi and xj and is a parameter mathematically expressed as configurations of data. The steps of the algorithm are base on sequential backward ranking, and they have been successfully tested on several real-world applications.
# b) Linear Regreesion
In statistics, linear regression refers to any approach to modeling the relationship between one or more variables denoted y and one or more variables denoted X, such that the model depends linearly on the unknown parameters to be estimated from the data.
Linear regression has many practical uses. Most applications of linear regression fall into one of the following two broad categories:
If the goal is prediction, or forecasting, linear regression can be used to fit a predictive model to an observed data set of y and X values. After developing such a model, if an additional value of X is then given without its accompanying value of y, the fitted model can be used to make a prediction of the value of y. Given a variable y and a number of variables X 1 , ..., X p that may be related to y, then linear regression analysis can be applied to quantify the strength of the relationship between y and the X j , to assess which X j may have no relationship with y at all, and to identify which subsets of the X j contain redundant information about y, thus once one of them is known, the others are no longer informative.
The core task of Data Mining Model is the application of the appropriate mining function to your data to build mining models that answer your business questions. Administrative tasks such as retrieving progress information or interpreting error messages support this task. Data Mining Process The Missing value technique used in these type of project is to take the mean of that feature but the data set which I have choose for the project have no missing values.
# d) Outlier Analysis
The technique used by data set to remove the outlier values is the Deviation based technique in which the human can easily distinguish unusual samples from a set of other similar samples.
After examining each and every data cluster, we obtain data set which contains no outlier.
# e) Data Reduction
The term data reduction in the context o data mining is usually applied to projects where the goal is to aggregate the information contained in large data sets into manageable(smaller) information nuggets. Data reduction method can include simple tabulation ,aggregation (computing descriptive statistics) or more sophisticated technique like principle component analysis.
Since the data which I have used in the project is not so huge therefore there is no need of applying the data reduction because it could lead to the loss of information from the data.
# f) Model Estimation
A model can be defined as a number of examples or a mathematical relationship. Data mining experts select and apply various mining functions because we can use different mining functions for the same type of data mining problem. Some of the mining functions require specific data types.
# g) Linear Regression
Regression: The purpose of this model function is to map a data item to a real-valued prediction variable.
The goal of regression is to build a concise model of the distribution of the dependent attribute in terms of the predictor attributes. The resulting model is used to assign values to a database of testing records, where the values of the predictor attributes are known but the dependent attribute is to be determined.
The value r 2 is a fraction between 0.0 and 1.0, and has no units. An r 2 value of 0.0 means that knowing X does not help you predict Y. There is no linear relationship between X and Y, and the best-fit line is a horizontal line going through the mean of all Y values. Since the error is very small so the result which we get after applying is very close to the final result. The graph between observed and fitted value is shown in figure
The normal probability plot is a special case of the probability plot. We cover the normal probability plot separately due to its importance in many applications. The normal probability plot is formed by: Vertical axis: Ordered response values Horizontal axis: Normal order statistic medians The normal probability plot is shown in the figure h) Cluster Analysis: Cluster analysis or clustering is the assignment of a set of observations into subsets (called clusters) so that observations in the same cluster are similar in some sense. Clustering is a method of unsupervised learning, and a common technique for statistical data analysis used in many fields, including machine learning, data Divisive: This is a "top down" approach: all observations start in one cluster, and splits are performed recursively as one moves down the hierarchy The K-means partitional-clustering algorithm is the simplest and most commonly used algorithm employing a square-error criterion.
It starts with a random, initial partition and keeps reassigning the samples to clusters, based on the similarity between samples and clusters, until a convergence criterion is met. The model in which every decision is based on the comparison of two numbers within constant time is called simply a decision tree model. It was introduced to establish computational complexity of sorting and searching, advantages of applying is Easy to understand, Map nicely to a set of business rules, Applied to real problems, Make no prior assumptions about the data, Able to process both numerical and categorical data.
Data mining techniques are used in a many research areas, including mathematics, cybernetics, genetics and marketing. Web mining, a type of data mining used in customer relationship management (CRM), takes advantage of the huge amount of information gathered by a Web site to look for patterns in user behavior.
![d) Modeling : Data mining experts select and apply various mining functions because you can use different mining functions for the same type of data mining problem. Some of the mining functions require specific data types. The data mining experts must assess each model. In the modeling phase, a frequent exchange with the domain experts from the data preparation phase is required. The modeling phase and the evaluation phase are coupled. They can be repeated several times to change parameters until optimal values are achieved. When the final modeling phase is completed, a model of high quality has been built. e) Evaluation : Data mining experts evaluate the model. If the model does not satisfy their expectations, they go back to the modeling phase and rebuild the model by changing its parameters until optimal values are achieved. When they are finally satisfied with the model, they can extract business explanations and evaluate the following questions: Does the model achieve the business objective? Have all business issues been considered? At the end of the evaluation phase, the data mining experts decide how to use the data mining results. f) Deployment : Data mining experts use the mining results by exporting the results into database tables or into other applications, for example, spreadsheets. a) Predictive Data Mining: Predictive data mining involves creation of model system based on and described by a given set of data. b) Descriptive Data Mining: Descriptive data mining on the other hand produces new and unique information inferred from the available set of data.](image-2.png "")
![Author ? : Department of Information Technology Bharati Vidyapeeth Deemed University College of Engineering, Pune-46. E-mail : awsit85@gmail.com Aws Saad Shawkat ? & H K Sawant ? a) Normalization of Raw Data Some data-mining methods, typically those that are based on distance computation between points in an n-dimensional space, may need normalized data for best results. Here are three simple and effective normalization techniques: b) Decimal Scaling Decimal scaling moves the decimal point but still preserves most of the original digit value. VI' =VI/10 K c) Min-Max Normalization](image-3.png "")
![Global Journal of Computer Science and Technology Volume XII Issue V Version I](image-4.png "")
![a) State the Problem A data mining project starts with the understanding of the problem. Data mining experts and domain experts work closely together to define the project objectives and the requirements from a business perspective. The project objective is then translated into a data mining problem definition. b) Data Normalization The use of the data transformation in my project is to make the data symmetric. In practice a suitable data transformation can be selected by examining the effect of the transformation.. So for the medical data set min-max transformation is often used. VI '= (VI-Min(VI))/(Max(VI)-Min(VI)) c) Missing Values Adjustment](image-5.png "")
2![equals 1.0, all points lie exactly on a straight line with no scatter. Knowing X lets you predict Y perfectly.](image-6.png "When r 2")
![Partition data into K clusters Parameter: Number of clusters (K) must be chosen Randomized initialization: Different clusters each time Non-deterministic Here the k-mean is applied to calculate the final cluster centers among samples.](image-7.png "")
© 2012 Global Journals Inc. (US)
© 2012 Global Journals Inc. (US) Global Journal of Computer Science and Technology Volume XII Issue V Version I
© 2012 Global Journals Inc. (US)
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Global Journal of Computer Science and Technology Volume XII Issue V Version I
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