As with all studies, this is based on looking at performance over certain time periods; other periods could be chosen to justify other conclusions. (kevinoninvesting.com)
A moving average is the average of the prices over a certain time period. (nadex.com)
The advance / decline line (A / D) is a technical indicator that plots changes in the value of the advance - decline index over a certain time period. (lplresearch.com)