Detrended fluctuation analysis

Detrended fluctuation analysis (DFA) is a way to measure how much a pattern changes over time. It can be used to find out if a pattern is random or if it is increasing or decreasing in a predictable way. To do this, DFA looks at how much the pattern changes from one point to the next.

Imagine you have an art project and you want to see if the pattern you made with your crayon changes over time. To figure this out, you might draw a straight line through the crayon pattern and then measure how far away each point in the pattern is from the line. DFA does the same thing except it looks at a longer period of time and uses math to measure the distances from the line. If the pattern is random, then the distances will be about the same over time. But if the pattern is increasing or decreasing in a predictable way, then the distances will increase or decrease too.