 Categorical data

In statistics, categorical data is that part of an observed dataset that consists of categorical variables, or for data that has been converted into that form, for example as grouped data. More specifically, categorical data may derive from either or both of observations made of qualitative data, where the observations are summarised as counts or cross tabulations, or of quantitative data, where observations might be directly observed counts of events happening or they might counts of values that occur within given intervals. Often, purely categorical data are summarised in the form of a contingency table. However, particularly when considering data analysis, it is common to use the term "categorical data" to apply to data sets that, while containing some categorical variables, may also contain noncategorical variables.
See also
 List of analyses of categorical data
 Qualitative data
References
 Andersen, Erling B. 1980. Discrete Statistical Models with Social Science Applications. North Holland, 1980.
 Bishop, Y. M. M.; Fienberg, S. E.; Holland, P. W. (1975). Discrete Multivariate Analysis: Theory and Practice. MIT Press. ISBN 9780262021135. MR381130.
 Christensen, Ronald (1997). Loglinear models and logistic regression. Springer Texts in Statistics (Second ed.). New York: SpringerVerlag. pp. xvi+483. ISBN 0387982477. MR1633357.
 Lauritzen, Steffen L. (2002 electronic (1979, 1982, 1989)). Lectures on Contingency Tables (updated electronic version of the (University of Aalborg) 3rd (1989) ed.). http://www.stats.ox.ac.uk/~steffen/papers/cont.pdf.
 NIST/SEMATEK (2008) Handbook of Statistical Methods
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