 Hi, it's Ryan. The term is an AB design. An AB design is a single subject design consisting of two conditions. The baseline condition, A, followed by the treatment condition, B. An example for that would be your existing diet that you're on is an A condition, followed by the new diet that you're trying, a B condition. You could also not water your lawn for a period of time. An A condition followed by watering your lawn, a B condition. Thank you.