Matter of fact, the researchers found that a person owning an iPhone gave them a 69.1% chance to correctly infer that the owner of the device had a "high-income", which they defined as being in the top quartile of income.
However, the iPhone is an even stronger indicator. "Cultural distances in the United States over time", was penned by Marianna Bertrand and Emir Kamenica of the University of Chicago.
The researchers say that knowing someone owns an iPhone gives them a 69 percent chance to infer correctly that the owner was "high-income". After all, iPhones were only introduced in 2007. The fourth-best brand indicator was if someone used Kikkoman soy sauce-a sign of wealth since 1992, when using Grey Poupon Dijon mustard was the number one indication you had plenty of cash.
The iPhone is a luxury product that is usually priced higher than competing smartphones. Since the data is from 2016, it doesn't take into account the $999 Apple iPhone X that was released in November 2017.
While the actual report isn't what you would call a page turner, it does say that based on 2016 data, no other brand is as "predictive" of having a high income as the Apple iPhone is. The data included bi-annual questionnaires and information obtained from face-to-face interviews such as household income.
In addition to research about preferred brands, the NBER paper also includes tables on which TV shows, movies, and magazines high-income households tend to read.
The researchers also used a machine learning algorithm to look at how different groups have had their preferences diverge over time. Their conclusion "runs against the popular narrative of the USA becoming an increasingly divided society", they said.