A statistical technique used to determine a trend in a time-ordered set of data (time series, single case design). In its simple form, a moving average is calculated by averaging initial subset of the data set (e.g., first 3 numbers), averaging successive subsets of the data series by excluding the first number of the previous subset and including the next value in the subset. The trend line that is produced by a moving average smooths out the variability of the data set, while being sensitive to changes in trend within a phase.