(NASDAQ:AMZN) investors hit the panic button today, with the stock selling off to the tune of nearly 10% after the company reported earnings that missed analysts' consensus expectations by a pretty wide margin.

However, earnings per share isn't the only number investors need to look to here. In this video, host Mark Reeth talks with Motley Fool analyst Brendan Mathews about the key numbers he looks at in tracking Amazon's performance. Brendan looks at the company's sales growth, which was up 20% year over year, and he also looks at Amazon's operating cash flow, which was up 10%. Including these numbers in an analysis of the company paints a broader picture of Amazon's quarter than just looking at earnings per share, and Brendan sees it as having been a good quarter overall.

On the business side of things, Brendan sees a number of exciting initiatives that Amazon is investing in today. He sees huge growth in Amazon Prime membership numbers and upgrades to the company's Kindle tablet and its Amazon Prime streaming video content library, and says that as long as Jeff Bezos is still at the helm, the company has an enormous amount of growth ahead. He doesn't see a single quarter's earnings miss as a cause for concern, and is definitely a buyer on today's pullback.