Quantitative relationships fall into the following categories:

• ordinal or nominal comparisons – differences across a list of ordered or unordered values for a set of items, groups or categories
• time series – how something changes over time (eg yearly)
• part to whole – ratio of each part to the whole, expressed as either percentages (with a total of 100%) or proportions of an absolute total (eg total income)
• deviation – difference between 2 sets of values (typically a set of measures compared with a baseline or prior measurement of the same variable)
• distribution – counts of values per interval of a continuous variable
• correlation – a set of 2 measurements that vary together (eg height and weight)
• geographic or spatial – comparison of data across a map (see Maps).