So then you reject the demographic information cited in the article as incorrect? What makes you conclude that Barna would publish what you conclude is poor research?
The information MIGHT be true to some extent. The lamestream media COUNT on folks, perhaps like you, to unquestioningly believe whatever is on the printed page and comes from the mouths of whatever "news anchor."
Poor research is also INSUFFICIENT research and when folks have a deadline to meet I do believe that they actually MIGHT cut some corners.
As for "statistics" see below.
https://en.wikipedia.org/wiki/Lies,_damned_lies,_and_statistics
The term was popularized in United States by Mark Twain (among others), who attributed it to the British Prime Minister Benjamin Disraeli: "There are three kinds of lies: lies, damned lies, and statistics."
Google: The Barna Group is an evangelical Christian polling firm based in Ventura, California.
Even evangelical Christian polling firms can make an error every so often since they are, like all of us, flawed human beings.