Data set

Data set

A data set (or dataset) is a collection of data, usually presented in tabular form. Each column represents a particular variable. Each row corresponds to a given member of the data set in question. Its values for each of the variables, such as height and weight of an object or values of random numbers. Each value is known as a datum. The data set may comprise data for one or more members, corresponding to the number of rows.

Nontabular data sets can take the form of marked up strings of characters, such as an XML file.

Almost all data sets, although they may often be written using high-level languages and base-ten numbers, end up transcoded into machine language for processing by the computers involved. Thus, for all their semantic diversity and tabular or nontabular forms, most datasets can be expressed in binary code as a long string of zeros and ones.

Contents

History

Historically, the term originated in the mainframe field, where it had a well-defined meaning, very close to contemporary computer file[citation needed]. This topic is not covered here.

Properties

A data set has several characteristics which define its structure and properties. These include the number and types of the attributes or variables and the various statistical measures which may be applied to them such as standard deviation and kurtosis.[1]

In the simplest case, there is only one variable, and then the data set consists of a single column of values, often represented as a list. In spite of the name, such a univariate data set is not a set in the usual mathematical sense, since a given value may occur multiple times. Normally the order does not matter, and then the collection of values may be considered to be a multiset rather than an (ordered) list[original research?].

The values may be numbers, such as real numbers or integers, for example representing a person's height in centimeters, but may also be nominal data (i.e., not consisting of numerical values), for example representing a person's ethnicity. More generally, values may be of any of the kinds described as a level of measurement. For each variable, the values will normally all be of the same kind. However, there may also be "missing values", which need to be indicated in some way.

In statistics data sets usually come from actual observations obtained by sampling a statistical population, and each row corresponds to the observations on one element of that population. Data sets may further be generated by algorithms for the purpose of testing certain kinds of software. Some modern statistical analysis software such as PSPP still present their data in the classical data set fashion.

Classic data sets

Several classic data sets have been used extensively in the statistical literature:

  • Bayesian Data Analysis - Data used in the book are provided on-line by Andrew Gelman, one of the book's authors.
  • The Bupa liver data, used in several papers in the machine learning (data mining) literature.

See also

Notes

External links


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • data set — data ,set noun count COMPUTING an amount of information stored as a file on a computer …   Usage of the words and phrases in modern English

  • data set — UK / US noun [countable] Word forms data set : singular data set plural data sets computing an amount of information stored as a file on a computer …   English dictionary

  • Data Set — I Data Set   [engl.], Datenverwaltung: Dateneinheit. II Data Set   [dt. »Datenübertragungseinrichtung«], Datenübertragung: DCE …   Universal-Lexikon

  • Data Set Ready —   [Abk. DSR, dt. »Betriebsbereitschaft«], Bezeichnung für eine Steuerleitung der seriellen Schnittstelle, mit der die Datenübertragungseinrichtung (z. B. Modem) der Datenendeinrichtung (z. B. PC) anzeigt, dass sie betriebsbereit ist …   Universal-Lexikon

  • data set — data and accompanying documentation which relate to a specific theme, e.g. catches by vessel type for a certain year, counts and measurements used in describing a fish species …   Dictionary of ichthyology

  • Data set (IBM mainframe) — This article is about mainframe computer file. For a general meaning in computing field, see Data set. data set (archaic), dataset (preferred), is a computer file having a record organization. The term pertains to the IBM mainframe operating… …   Wikipedia

  • data set trailer label — baigiamoji žymė statusas T sritis automatika atitikmenys: angl. data set trailer label; trailer label vok. Dateiendeetikett, n; Dateiendekennsatz, m; Nachsatz, m rus. концевая метка, f pranc. label de fin, m …   Automatikos terminų žodynas

  • Data set — Ein Dataset bezeichnet eine größere, zusammenhängende Datenmenge, nicht zu verwechseln mit einem Datensatz einer Datenbanktabelle. Im Detail hat der Begriff aber je nach Kontext unterschiedliche Bedeutungen: Dataset, IBM Großrechner Hier ist… …   Deutsch Wikipedia

  • data set — Computers. 1. a collection of data records for computer processing. 2. modem. [1970 75] * * * …   Universalium

  • data set —    1. AT&T name for modem.    2. A collection of related data …   IT glossary of terms, acronyms and abbreviations

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”