Classification in the context of Classification scheme (information science)

Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation of things to the classes (classification).

Originally, taxonomy referred only to the classification of organisms on the basis of shared characteristics. Today it also has a more general sense. It may refer to the classification of things or concepts, as well as to the principles underlying such work. Thus a taxonomy can be used to organize species, documents, videos or anything else.

The category of newly industrialized country (NIC), newly industrialized economy (NIE) or middle-income country is a socioeconomic classification applied to several countries around the world by political scientists and economists. They represent a subset of developing countries whose economic growth is much higher than that of other developing countries; and where the social consequences of industrialization, such as urbanization, are reorganizing society.

Information science (sometimes abbreviated as infosci) is an academic field which is primarily concerned with analysis, collection, classification, manipulation, storage, retrieval, movement, dissemination, and protection of information. Practitioners within and outside the field study the application and the usage of knowledge in organizations in addition to the interaction between people, organizations, and any existing information systems with the aim of creating, replacing, improving, or understanding the information systems.

A combat sport, or fighting sport, is a contact sport that usually involves one-on-one combat. In many combat sports, a contestant wins by scoring more points than the opponent, submitting the opponent with a hold, disabling the opponent (knockout, KO), or attacking the opponent in a specific or designated technique. Combat sports share a long history with the martial arts.

Some combat sports (and their national origin) include boxing (Greek-British), Brazilian jiu-jitsu (Japanese-Brazilian), catch wrestling (British-American), jujutsu (Japanese), judo (Japanese), freestyle wrestling (British-American), Greco-Roman wrestling (French), karate (Chinese-Okinawan-Japanese), kickboxing (numerous origins, mainly Southeast Asian), Lethwei (Burmese), mixed martial arts (numerous origins), Muay Thai (Thai), sambo (Soviet/Russian), sanda (Chinese), savate (French), taekwondo (Korean), Vale Tudo (Brazilian), pankration (Ancient Greek), luta livre (Brazilian), and folk wrestling (various).

In information science and ontology, a classification scheme is an arrangement of classes or groups of classes. The activity of developing the schemes bears similarity to taxonomy, but with perhaps a more theoretical bent, as a single classification scheme can be applied over a wide semantic spectrum while taxonomies tend to be devoted to a single topic.

In the abstract, the resulting structures are a crucial aspect of metadata, often represented as a hierarchical structure and accompanied by descriptive information of the classes or groups. Such a classification scheme is intended to be used for the classification of individual objects into the classes or groups, and the classes or groups are based on characteristics which the objects (members) have in common.

The sport of sailing involves a variety of competitive sailing formats that are sanctioned through various sailing federations and yacht clubs. Racing disciplines include matches within a fleet of sailing craft, between a pair thereof or among teams. Additionally, there are specialized competitions that include setting speed records. Racing formats include both closed courses and point-to-point contests; they may be in sheltered waters, along coasts, or on the open ocean. Most competitions are held within defined classes or ratings that either entail one type of sailing craft to ensure a contest primarily of skill or rating the sailing craft to create classifications or handicaps.

On the water, a sailing competition among multiple vessels is called a regatta. A regatta consists of multiple individual races. The boat crew that performs best over the series of races is the overall winner. There is a broad variety of races and of sailboats used for racing, from large yacht to dinghy racing. Much racing is done around buoys or similar marks in protected waters, while some longer offshore races cross open water. Boats used for racing include small dinghies, catamarans, boats designed primarily for cruising, and purpose-built raceboats. The Racing Rules of Sailing govern the conduct of yacht racing, windsurfing, kitesurfing, model boat racing, dinghy racing, and virtually any other form of racing around a course with more than one vessel while powered by the wind.

When classification is performed by a computer, statistical methods are normally used to develop the algorithm.

Often, the individual observations are analyzed into a set of quantifiable properties, known variously as explanatory variables or features. These properties may variously be categorical (e.g. "A", "B", "AB" or "O", for blood type), ordinal (e.g. "large", "medium" or "small"), integer-valued (e.g. the number of occurrences of a particular word in an email) or real-valued (e.g. a measurement of blood pressure). Other classifiers work by comparing observations to previous observations by means of a similarity or distance function.

Hierarchical classification is a system of grouping things according to a hierarchy.

In the field of machine learning, hierarchical classification is sometimes referred to as instance space decomposition, which splits a complete multi-class problem into a set of smaller classification problems.

In machine learning, supervised learning (SL) is a type of machine learning paradigm where an algorithm learns to map input data to a specific output based on example input-output pairs. This process involves training a statistical model using labeled data, meaning each piece of input data is provided with the correct output. For instance, if you want a model to identify cats in images, supervised learning would involve feeding it many images of cats (inputs) that are explicitly labeled "cat" (outputs).

The goal of supervised learning is for the trained model to accurately predict the output for new, unseen data. This requires the algorithm to effectively generalize from the training examples, a quality measured by its generalization error. Supervised learning is commonly used for tasks like classification (predicting a category, e.g., spam or not spam) and regression (predicting a continuous value, e.g., house prices).

Binary classification is the task of putting things into one of two categories (each called a class). As such, it is the simplest form of the general task of classification into any number of classes. Typical binary classification problems include:

• Medical testing to determine if a patient has a certain disease or not;
• Quality control in industry, deciding whether a specification has been met;
• In information retrieval, deciding whether a page should be in the result set of a search or not
• In administration, deciding whether someone should be issued with a driving licence or not
• In cognition, deciding whether an object is food or not food.

When measuring the accuracy of a binary classifier, the simplest way is to count the errors. But in the real world often one of the two classes is more important, so that the number of both of the different types of errors is of interest. For example, in medical testing, detecting a disease when it is not present (a false positive) is considered differently from not detecting a disease when it is present (a false negative).

In mathematics, a classification theorem answers the classification problem: "What are the objects of a given type, up to some equivalence?". It gives a non-redundant enumeration: each object is equivalent to exactly one class.

A few issues related to classification are the following.

Governments and private organizations have developed car classification schemes that are used for various purposes including regulation, description, and categorization of cars.

The International Standard ISO 3833-1977 Road vehicles – Types – Terms and definitions also defines terms for classifying cars.

Categorization is a type of cognition involving conceptual differentiation between characteristics of conscious experience, such as objects, events, or ideas. It involves the abstraction and differentiation of aspects of experience by sorting and distinguishing between groupings, through classification or typification on the basis of traits, features, similarities or other criteria that are universal to the group. Categorization is considered one of the most fundamental cognitive abilities, and it is studied particularly by psychology and cognitive linguistics.

Categorization is sometimes considered synonymous with classification (cf., Classification synonyms). Categorization and classification allow humans to organize things, objects, and ideas that exist around them and simplify their understanding of the world. Categorization is something that humans and other organisms do: "doing the right thing with the right kind of thing." The activity of categorizing things can be nonverbal or verbal. For humans, both concrete objects and abstract ideas are recognized, differentiated, and understood through categorization. Objects are usually categorized for some adaptive or pragmatic purposes.