Over the past year, Apple (NASDAQ:AAPL) investors have expressed concern over the company's declining market share in certain markets, including the all-important "Greater China" geography. New estimates from Canalys say the Mac maker has slipped to the No. 6 spot, while local competitors along with Samsung grow their respective shares.

In the following video, Fool contributor Evan Niu, CFA, and Eric Bleeker, CFA, discuss the different estimates that investors should be mindful of, as well as how to parse different figures.