What is a mode?

The mode is the most frequently occurring value in the data set. Sometimes there is a bit of ambiguity in the selection of the mode. For example, two different values may both be tied for the most frequently occurring value. In this case, both values will be considered a mode of the data set.

Another situation where the mode is ambiguous is when no value in the data set occurs more than once. In this situation, any (and every) value is considered a mode.

A related statistics is the modal class. This is the most frequently occurring category when the data are classified into groups. The modal class, of course, will change depending on how wide or narrow your classifications are.

In a sample of adults, the LDL values are (in order from low to high): 1.84, 2.96, 3.49, 3.68, 3.72, 3.73, 3.84, 3.84, 4.14, 4.41, 4.80, 4.26, 5.57, and 5.85. For this data, the mode is 3.84, since that is the only data value which occurs twice in this data set. If we classified the data into groups like 1.00-1.99, 2.00-2.99, etc. the modal class would be 3.00-3.99.