vanity metric
n. A measurement or score that is used to impress other people, but is not a true indicator of quality or success.
Examples
2015
Use the social web and all the popular social media channels to connect with people who you know, and people you would like to meet — your target audience. It’s the same as a traditional networking event, network with like minded individuals. The trick with this is all about finding the correct people to connect with. Don’t be fooled with vanity metrics such as followers or the number of likes.
—Anton Koekemoer, “Setting goals on social media is absolutely imperative,” Memeburn, April 28, 2015
2013
The "quantified self" — AKA, in the words of writer and editor Paul Carr, "vanity metrics" — began in California, naturally, so that beautiful people could measure just how much more beautiful the number of steps they had taken were making them.
—Samuel Gibbs, et al., “Tech 128: PewdiePie, PS4, selfies and self-driving cars,” The Guardian (London), December 30, 2013
2011
But can you build a lean startup in a bubble (if we are still in one)? “It is even more important,” he says, to go lean when everyone is throwing money at “success theater” and showing off vanity metrics. “Vanity metrics are the numbers you want to publish on TechCrunch to make your competitors feel bad,” he says.
2007 (earliest)
And meanwhile, for the average observer not in the process of transacting an ad buy, it just muddies the waters as the agencies like Netratings and comScore publish these broad-based "rankings" of web properties that we're supposed to look at. These have always been vanity metrics, easy to manipulate and ostensibly useful for impressing people at cocktail parties.
—Andrew Goodman, “After the Page View: Can We Focus on the Question, Please?,” Traffick, July 10, 2007