# Orthogonal array testing

Orthogonal array testing is a black box testing technique that is a systematic, statistical way of software testing.[1][2] It is used when the number of inputs to the system is relatively small, but too large to allow for exhaustive testing of every possible input to the systems.[1] It is particularly effective in finding errors associated with faulty logic within computer software systems.[1] Orthogonal arrays can be applied in user interface testing, system testing, regression testing, configuration testing and performance testing. The permutations of factor levels comprising a single treatment are so chosen that their responses are uncorrelated and therefore each treatment gives a unique piece of information. The net effects of organizing the experiment in such treatments is that the same piece of information is gathered in the minimum number of experiments.

## Background

### Orthogonal vector

Orthogonal vectors exhibit orthogonality. Orthogonal vectors exhibit the following properties:

• Each of the vectors conveys information different from that of any other vector in the sequence, i.e., each vector conveys unique information therefore avoiding redundancy.
• On a linear addition, the signals may be separated easily.
• Each of the vectors is statistically independent of the others, i.e., the correlation between them is nil.
• When linearly added, the resultant is the arithmetic sum of the individual components.

## Benefits

• Testing cycle time is reduced and analysis is simpler.
• Test cases are balanced, so it's straightforward to isolate defects and assess performance. This provides a significant cost savings over pair-wise testing.

## References

1. ^ a b c Pressman, Roger S (2005). Software Engineering: A Practitioner's Approach (6th ed.). McGraw-Hill. ISBN 0-07-285318-2.
2. ^ Phadke, Madhav S. "Planning Efficient Software Tests". Phadke Associates, Inc. Numerous articles on utilizing Orthogonal Arrays for Software and System Testing.
3. ^ Dustin, Elfriede. "Orthogonally Speaking" (PDF). (subscription required)