“This lightbulb went off that almost no one was asking these questions.”In 2006, Elie Hassenfeld and a few of his friends pooled some money they wanted to donate to charity. And they wanted to find charities where their money would go the farthest in improving lives. That information, it turned out, was incredibly hard to find.That was the seed of GiveWell. For almost a decade, GiveWell has dedicated itself to rigorously researching the impact of charities around the world and channeling donations to the ones that are the most effective at saving lives. It might sound simple, but this was a radically new approach in the world of charitable giving, and the work itself isn’t simple at all.I’ve supported GiveWell through the years. So as the year winds down and other people might be thinking about giving to a charity, I wanted to invite Hassenfeld, GiveWell’s chief executive, on the show to talk through this work. How does it measure impact? Are there limits to what you can measure? As an organization, has it made mistakes? What does it really mean to give well?If you like what you hear, I hope you’ll also consider donating to GiveWell. Learn more at givewell.org.Mentioned:GiveWell“Trust in Radical Truth and Radical Transparency” by Ray DalioHarlem Children’s ZoneAgainst Malaria FoundationHelen Keller IntlNew IncentivesNo Lean SeasonClinton Health Access Initiative (CHAI)PATHGiveDirectlyALIMABook Recommendations:Factfulness by Hans Rosling with Ola Rosling and Anna Rosling RönnlundPoor Economics by Abhijit V. Banerjee and Esther DufloBehind the Beautiful Forevers by Katherine BooThoughts? Guest suggestions? Email us at ezrakleinshow@nytimes.com.You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast, and you can find Ezra on Twitter @ezraklein. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs.This episode of “The Ezra Klein Show” was produced by Jack McCordi