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Categorical data is the statistical data type consisting of categorical variables or of data that has been converted into that form, for example as grouped data. More specifically, categorical data may derive from observations made of qualitative data that are summarised as counts or cross tabulations , or from observations of quantitative data ...
A i is the number of data type A at sample site i, B i is the number of data type B at sample site i, K is the number of sites sampled and || is the absolute value. This index is probably better known as the index of dissimilarity (D). [44] It is closely related to the Gini index. This index is biased as its expectation under a uniform ...
Each entry in the table contains the frequency or count of the occurrences of values within a particular group or interval, and in this way, the table summarizes the distribution of values in the sample. This is an example of a univariate (=single variable) frequency table. The frequency of each response to a survey question is depicted.
The concept of data type is similar to the concept of level of measurement, but more specific. For example, count data requires a different distribution (e.g. a Poisson distribution or binomial distribution) than non-negative real-valued data require, but both fall under the same level of measurement (a ratio scale).
Another method of grouping the data is to use some qualitative characteristics instead of numerical intervals. For example, suppose in the above example, there are three types of students: 1) Below normal, if the response time is 5 to 14 seconds, 2) normal if it is between 15 and 24 seconds, and 3) above normal if it is 25 seconds or more, then the grouped data looks like:
Ordinal data analysis requires a different set of analyses than other qualitative variables. These methods incorporate the natural ordering of the variables in order to avoid loss of power. [ 1 ] : 88 Computing the mean of a sample of ordinal data is discouraged; other measures of central tendency, including the median or mode, are generally ...
The data include quantitative variables =, …, and qualitative variables =, …,.. is a quantitative variable. We note: . (,) the correlation coefficient between variables and ;; (,) the squared correlation ratio between variables and .; In the PCA of , we look for the function on (a function on assigns a value to each individual, it is the case for initial variables and principal components ...
RQDA is an R package for computer-assisted qualitative data analysis or CAQDAS, making it one of the few open source tools to assist qualitative coding of textual data.Note that there are also other popular but mostly proprietary CAQDAS tools such as NVivo and Atlas.ti but these software come at a cost.