Millennials are no longer living with their parents

As any journalist will tell you, companies love to survey millennials. (We get press releases on such surveys pretty much daily.) EY — the former Ernst & Young — is no exception: They've just released "The Millennial Economy 2018," which updates the data from a survey named "The Millennial Economy" that was conducted 2 years ago.

The big picture: Two big findings stand out. The proportion of millennials living with their parents has plunged, from 30% in 2016 to 16% in 2018. The proportion of millennials who own their own home has soared, from 26% in 2016 to 40% in 2018.

Our thought bubble: Firstly, all credit to EY for repeating its survey. This kind of data becomes much more interesting and informative when you have a time series, rather than just a single datapoint.

One note of caution: While the 2016 survey was conducted by Public Opinion Strategies and GBA Strategies, the 2018 survey was conducted by Research Now. None of those companies are household names, and EY did not respond to a query about why the change was made.

• While the numbers are surely directionally accurate, it's dangerous to read too much into the magnitude of the changes. When you start looking at the size of a change, rather than the absolute size of a number, then margins of error get magnified significantly.
• Millennials are 2 years older in 2018 than they were in 2016. The first survey was of individuals aged between 18 and 34; this year, it's of individuals aged 20 to 36. Who are naturally more likely to own homes and to no longer live with their parents.

The bottom line: Survey data can be informative and eye opening, but the more extraordinary the results, the less likely they are to be true. Millennials have certainly been buying houses in the past two years, but this isn't enough evidence to conclude that the millennial homeownership rate has jumped by 54% in just 24 months.