The most frequently occurring value in a group of measurements The most common value obtained in a set of observations. For example, for a data set (3, 7, 3, 9, 9, 3, 5, 1, 8, 5), the unique mode is 3. Similarly, for a data set (2, 4, 9, 6, 4, 6, 6, 2, 8, 2), there are two modes: 2 and 6.