-Cases are the objects described by a set of data. May be customers, companies, subjects in a study, or other objects.
-Label variable is a special variable used in some data sets to distinguish the different cases (similar to an ID).
-Variable is a characteristic of a case.
-Data are the actual values of variables. The data collected in a particular study are referred to as the data set.
-A categorical variable places a case into one of several groups, or categories. The data of a categorical variable are called categorical data.
-A quantitative variable takes numerical values for which arithmetic operations make sense. The data of a quantitative variable are called quantitative data.
-Nominal scale: Data are simply labels or categories, distinct categories in which no ranking is implied.
-Ordinal scale: Data can be used to rank, or order, the observation. (Ordered Categorical)
-Interval scale: Data has the properties of ordinal scale in which the difference between measurements is a meaningful quantity but does not involve a true zero point. Must be numeric.
-Ratio scale: Data has the properties of ordinal scale in which the difference between measurements is a meaningful quantity and involves a true zero point. Must be numeric.