A friend recently expressed displeasure with trendy names like “Brody” and “Jayden.” Yahoo answers suggests he has company [1][2][3], as well as that there are characteristic vowel patterns common to neopraenomina. Often,  “a” is replaced with “ay” or “ae” to represent the sound /eI/ (s/Jaden/Jayden), and “i” with “y” to represent /I/ (s/Kaitlin/Kaitlyn).

It could be that trendy names attract revulsion because they're more common among current teenagers and pre-teens. So it's probably more likely that a Jayden would cut through your lawn, crushing your gardenias, than a Matt, or for that matter, a Mortimer.

The Social Security Administration’s names database confirms that trendy names are younger, on average. Here's the percentage of the population named "Brody" over time.

What other names share this signature, and are trendy by some statistical measure? I  picked "Brody" as an arbitrary trendy name in the names database, and searched for names with the most closely correlated time series.

Here they are, normalized by max value and smoothed in a three year window, for the 50 names most highly correlated with “Brody”. The darkest line is “Brody,” with lighter lines less correlated.

The top ten most correlated trendy names are Dalilah, Hayden, Grayden, Ailey, Sahana, Braylan, Camila, Jaslynn, and Rhylie.

What are the least correlated names? Are they Biblical names? Are they names that sound “classical?” Here are their time series, also normalized by max value and smoothed in a three year window:

These names seem to surge in the late 1800s and dip in the early 20th century. Then they peak out again around 1920, and wane steadily to zero in the present day. Here's a table of both sets of names:

The uncorrelated names aren’t Biblical, but they do seem really old. They’re also all female names. Next: consider male and female names separately. Code is available here. Data is available here.