ByWilliam P. Barrett,

Senior Contributor.

By phone, by TV, by stream, by email and text messages, on social media, in person: Americans are bombarded with ever more pleas from charities, particularly at the end of the year. With two million tax-exempt nonprofits in the U.S.—an astonishing one for every 165 residents—there’s likely to be some new charity that catches your attention. Should you take a risk and donate?

The new Forbes list of America’s top 100 charities describes the biggest, collectively receiving $66.5 billion in private contributions, more than one-tenth of the $592 billion given to all nonprofits, according to Giving USA Foundation.

Yet the data presented in the Forbes list, along with some simple analytical techniques and a little Internet digging, can help you evaluate almost any charity, big or small, that catches your attention. View the whales as teaching examples for the minnows. Don’t be scared off by a lot of zeros after a digit on a financial filing.