Chapter Summary

Data describe characteristics of a collection of cases or observations. Data for statistical analysis are typically arranged in a data table. The rows of the table identify the cases. The columns of the table denote variables, with each column containing the measured values of some attribute of the cases. Variables may be numerical or categorical. Numerical variables have common measurement units, and it makes sense to average these values. Categorical variables identify cases with a shared label. Ordinal variables, such as those from Likert scales, order the cases and may assign numerical labels; these are often treated as numerical data. Recoding a variable reduces the number of distinct values; aggregating a variable reduces ...

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