total degrees of freedom
the total number of observations in an analysis minus one. For example, in an experiment in which there are 4 conditions, with 20 participants randomly assigned to each condition, there are 80 independent observations: The total degrees of freedom is 79 (80 – 1) observations, as there is one constraint on any value that will be computed to describe the sample, such as the mean. Relatedly, each individual condition has its own degrees of freedom as well: 20 – 1 = 19.