I am reading this classic paper(http://www.business.unr.edu/faculty/liuc/files/BADM742/Jegadeesh_Titman_1993.pdf) and got confused by one of their arguments on their overlapping portfolio strategy to test momentum. They claimed on page 68:
To increase the power of our tests, the strategies we examine include portfolios with overlapping holding periods.
I don't quite sure why overlapping holding periods increase the power of their statistical test. Can someone please give an intuitive explanation?