A method of illustrating relationships and patterns in system behaviors by representing two or more system variables in a controlled way.
People understand the way the world works by identifying relationships and patterns in or between systems. One of the most powerful methods of identifying and understanding these relationships is to represent information in controlled ways so that comparisons can be made. Key techniques for making valid comparisons are apples to apples, single contexts, and benchmarks.
Apples to Apples
Comparing apples to apples means comparing things that can reasonably be compared, while the phrase apples to oranges often is used to represent a comparison that is unreasonable or perhaps impossible.
For example, when comparing crime rates of different countries, it is necessary to account for differences in variables such as population, types of laws, and level of law enforcement. Otherwise, conclusions based on the comparison will be unreliable. Common methods of ensuring apples-to-apples comparisons include clearly disclosing details of how variables were measured, making corrections to the data as necessary to eliminate confounding variables, and representing the variables using the same graphical and numerical standards.
Single Context
Comparison data should be presented in a single context, so that subtle differences and patterns in the data are detectable.
For example, the ability to detect patterns across multiple graphs is lower if the graphs are located on separate pages versus the same page. Common methods of representing information in single contexts include the use of a small number of displays that combine many variables (versus many separate displays) and multiple small views of system states (known as small multiples) in a single display (versus multiple displays).
Benchmarks
Claims about evidence or phenomena should be accompanied by benchmark variables so that clear and substantive comparison can be made.
For example, Apple usually compares any new device performance against the old version – and current technologies available on the market. That gives the value to the Comparison.