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Tetrad is a discrimination test designed to determine whether a noticeable difference exists between two products. In a Tetrad test, panelists receive four samples – two of sample A and two of sample B – and are asked to group the like pairs together. The nature of the difference is typically not specified.

Tetrad testing has gained significant popularity in recent years as an alternative to other discrimination methods, particularly triangle testing. Despite using four samples instead of three, research demonstrates that Tetrad's greater statistical power allows it to achieve the same level of sensitivity as triangle testing with far fewer results. According to research by Ennis and Rousseau, Tetrad requires only one-third of the responses needed by triangle testing to reach equivalent sensitivity levels.

This efficiency translates directly to cost savings. With fewer results required to achieve the same – or better – confidence in your data, organizations can reduce expenses associated with test administration time and panelist compensation.