The Orthogonal Array Testing Strategy (OATS) is a 
systematic, statistical way of testing pair-wise
interactions. It provides representative (uniformly 
distributed) coverage of of all variable pair
combinations. This makes the technique particularly useful 
for integration testing of software
components (especially in OO systems where multiple 
subclasses can be substituted as the server for a
client). It is also quite useful for testing combinations 
of configurable options (such as a web page that
lets the user choose the font style, background color, and 
page layout).