A cute interactive feature: "How Y’all, Youse and You Guys Talk" ("What does the way you speak say about where you’re from? Answer all the questions below to see your personal dialect map"), NYT 12/21/2013. The description:
Most of the questions used in this quiz are based on those in the Harvard Dialect Survey, a linguistics project begun in 2002 by Bert Vaux and Scott Golder. The original questions and results for that survey can be found on Dr. Vaux's current website.
The data for the quiz and maps shown here come from over 350,000 survey responses collected from August to October 2013 by Josh Katz, a graphics editor for the New York Times who developed this quiz. The colors on the large heat map correspond to the probability that a randomly selected person in that location would respond to a randomly selected survey question the same way that you did. The three smaller maps show which answer most contributed to those cities being named the most (or least) similar to you.
For more about the background, see Ben Zimmer's post "About those dialect maps making the rounds", 6/6/2013.
Here's my map, or at least one version of it:
The "specific cities" feature is a bit random — mine are "Baltimore" and "Saint Louis", both attributed to the fact that (like a large minority of other Americans) I lack the caught/cot merger, and "Newark/Paterson", attributed to the term "mischief night" for the night before Halloween:
"Mischief night" is one of those phrases that I've heard around, maybe when I lived in northern New Jersey for a while, though we had no such concept when I was growing up (since mischief took place on Halloween itself). The survey has a few other features like those, which tag you with particular not-necessarily-relevant cities.
I haven't been able to find a description of the algorithm used to combine information from the various maps. But there seems to be a problem, either in the interpretation of the answers or in the method of combining them, as indicated by the fact that my final map has got a lot of orange and red below the Mason-Dixon line, despite the information that I'm not a y'all speaker. The map for the y'all choice seems plausible:
But something seems to be wrong in the interpretation of not making this choice, or the method for combining choices into a final geographical pattern, or both.
One issue might just be the way of asking the questions. Though I obviously know about y'all, I'd never use it except as a joke or quotation or imitation, and similarly for you'uns and youse. Those are positive markers of geo-social identity, while choices like you all and you are mostly negative markers, in the sense that their interpretation depends mostly on NOT having made the other choices.
But the real usage distribution of such alternatives may not emerge accurately from answers to questions like this. Some southerners may consider y'all to be non-standard, for example, and therefore give answers like you or you all.
Or maybe this app's method for combining evidence is suboptimal…