Data Mining by Mehmed Kantardzic (inspirational novels TXT) 📗

in monitoring, controlling, and improving their operations. Scientists are at the higher end of today’s data-collection machinery, using data from different sources—from remote-sensing platforms to microscope probing of cell details. Scientific instruments can easily generate terabytes of data in a short period of time and store them in the computer. One example is the hundreds of terabytes of DNA, protein-sequence, and gene-expression data that biological science researchers have gathered at steadily increasing rates. The information age, with the expansion of the Internet, has caused an exponential growth in information sources and also in information-storage units. An illustrative example is given in Figure 1.3, where we can see a dramatic increase in Internet hosts in recent years; these numbers are directly proportional to the amount of data stored on the Internet.

Figure 1.3. Growth of Internet hosts.

It is estimated that the digital universe consumed approximately 281 exabytes in 2007, and it is projected to be 10 times that size by 2011. (One exabyte is ∼1018 bytes or 1,000,000 terabytes). Inexpensive digital and video cameras have made available huge archives of images and videos. The prevalence of Radio Frequency ID (RFID) tags or transponders due to their low cost and small size has resulted in the deployment of millions of sensors that transmit data regularly. E-mails, blogs, transaction data, and billions of Web pages create terabytes of new data every day.

There is a rapidly widening gap between data-collection and data-organization capabilities and the ability to analyze the data. Current hardware and database technology allows efficient, inexpensive, and reliable data storage and access. However, whether the context is business, medicine, science, or government, the data sets themselves, in their raw form, are of little direct value. What is of value is the knowledge that can be inferred from the data and put to use. For example, the marketing database of a consumer goods company may yield knowledge of the correlation between sales of certain items and certain demographic groupings. This knowledge can be used to introduce new, targeted marketing campaigns with a predictable financial return, as opposed to unfocused campaigns.

The root of the problem is that the data size and dimensionality are too large for manual analysis and interpretation, or even for some semiautomatic computer-based analyses. A scientist or a business manager can work effectively with a few hundred or thousand records. Effectively mining millions of data points, each described with tens or hundreds of characteristics, is another matter. Imagine the analysis of tera­bytes of sky-image data with thousands of photographic high-resolution images (23,040 × 23,040 pixels per image), or human genome databases with billions of components. In theory, “big data” can lead to much stronger conclusions, but in practice many difficulties arise. The business community is well aware of today’s information overload, and one analysis shows that

1. 61% of managers believe that information overload is present in their own workplace,

2. 80% believe the situation will get worse,

3. over 50% of the managers ignore data in current decision-making processes because of the information overload,

4. 84% of managers store this information for the future; it is not used for current analysis, and

5. 60% believe that the cost of gathering information outweighs its value.

What are the solutions? Work harder. Yes, but how long can you keep up when the limits are very close? Employ an assistant. Maybe, if you can afford it. Ignore the data. But then you are not competitive in the market. The only real solution will be to replace classical data analysis and interpretation methodologies (both manual and computer-based) with a new data-mining technology.

In theory, most data-mining methods should be happy with large data sets. Large data sets have the potential to yield more valuable information. If data mining is a search through a space of possibilities, then large data sets suggest many more possibilities to enumerate and evaluate. The potential for increased enumeration and search is counterbalanced by practical limitations. Besides the computational complexity of the data-mining algorithms that work with large data sets, a more exhaustive search may also increase the risk of finding some low-probability solutions that evaluate well for the given data set, but may not meet future expectations.

In today’s multimedia-based environment that has a huge Internet infrastructure, different types of data are generated and digitally stored. To prepare adequate data-mining methods, we have to analyze the basic types and characteristics of data sets. The first step in this analysis is systematization of data with respect to their computer representation and use. Data that are usually the source for a data-mining process can be classified into structured data, semi-structured data, and unstructured data.

Most business databases contain structured data consisting of well-defined fields with numeric or alphanumeric values, while scientific databases may contain all three classes. Examples of semi-structured data are electronic images of business documents, medical reports, executive summaries, and repair manuals. The majority of Web documents also fall into this category. An example of unstructured data is a video recorded by a surveillance camera in a department store. Such visual and, in general, multimedia recordings of events or processes of interest are currently gaining widespread popularity because of reduced hardware costs. This form of data generally requires extensive processing to extract and structure the information contained in it.

Structured data are often referred to as traditional data, while semi-structured and unstructured data are lumped together as nontraditional data (also called multimedia data). Most of the current data-mining methods and commercial tools are applied to traditional data. However, the development of data-mining tools for nontraditional data, as well as interfaces for its transformation into structured formats, is progressing at a rapid rate.

The standard model of structured data for data mining is a collection of cases. Potential measurements called features are specified, and these features are uniformly measured over many cases. Usually the representation of structured data for data-mining problems is in a tabular form, or in the form of a single relation (term used in relational databases), where columns are features of objects stored in a table and