Among the more difficult challenges I faced when I was researching “The Wired City” was trying to figure out the influence — and thus the effectiveness — of the New Haven Independent, the nonprofit online-only news site that is the major focus of the book. So I was intrigued when NPR reported last week that the folks who run Charity Navigator hope to unveil effectiveness ratings for nonprofits in 2016. I suspect it won’t be easy. Nonprofit news presents special challenges. You can measure a foo...