While Wall Street myopically focuses on a few numbers, like revenue, earnings, and price-to-earnings, you would be better off following another metric. Since companies -- especially tech ones -- thrive on the profits they earn from innovate products and services, you would be better off understanding how research and development spending relates to a company's profitability.

In the video below, Fool contributor Kevin Chen reveals the one metric every investor should know. He also walks you through how you can use this metric to inform your buy or sell thesis for IBM (NYSE:IBM)Baidu (NASDAQ:BIDU)Apple (NASDAQ:AAPL)Google (NASDAQ:GOOGL), and Nokia (NYSE:NOK).

Fool contributor Kevin Chen owns shares of Baidu. The Motley Fool recommends Apple, Baidu, and Google. The Motley Fool owns shares of Apple, Baidu, Google, and International Business Machines.. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.