My hypothesis is names that begin traditionally for boys lose popularity for boys when they start being given to girls.

I found an article from https://www.parents.com called “Ashley, Sydney, and 20 Other Girls’ Names that Used to Be Boys’ Names.” I checked all 22 names one at a time. An individual name would show correlation if an X appeared from a negative slope on the boy’s line intersecting a positively-sloped girl’s line.

This article gave way to a second hypothesis of A female celebrity or TV/film character will popularize one of these unisex/boy’s names for girls and solidify it as a “girl’s name.” This is because https://www.parents.com singled out six of the names for having such a reason.

The 22 names tested are: Ashley, Avery, Allison, Aubrey, Beverly, Blair, Carol, Dana, Darcy, Gale, Hilary, Lindsay, Lynn, Meredith, Morgan, Quinn, Reagan, Sandy, Sydney, Taylor, Vivian, and Whitney.

The article can be found here https://www.parents.com/baby-names/ideas/origin/ashley-sydney-and-20-other-girls-names-that-used-to-be-boys-names/

Required Packages

library(tidyverse)
library(babynames)

First Hypothesis

Correlation

I found a correlation for seven of the 22 names: Aubrey, Blair, Gale, Hilary, Lynnn, Meredith, and Quinn.

Aubrey
babynames %>% 
  filter(name %in% "Aubrey") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> aubreyplot

aubreyplot + geom_vline(xintercept = 1974, color = "navyblue", linetype = "dotted")

Aubrey for boys peaked after Aubrey was introduced for girls. However, boys declined at a similar time to girls picking up speed, in the mid 1970’s. The line is at 1974.

Blair
babynames %>% 
  filter(name %in% "Blair") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> blairplot

blairplot + geom_vline(xintercept = 1979, color = "navyblue", linetype = "dotted")

Blair was much more popular for boys than girls, and switches at 1979 which is when Facts of Life premiered. Blair remained popular for boys for decades after it was introduced for girls.

Gale
babynames %>% 
  filter(name %in% "Gale") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> galeplot

galeplot + geom_vline(xintercept = 1940, color = "navyblue", linetype = "dotted")

Gale gained popularity for boys after being introduced for girls. Decades later, around 1940, Gale got much more popular for girls and dropped out of favor for boys almost entirely

Hilary
babynames %>% 
  filter(name %in% "Hilary") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> hilaryplot

hilaryplot + geom_vline(xintercept = 1943, color = "navyblue", linetype = "dotted")

Hilary became more popular for girls in the early 1940’s about 20 years after being introduced, that was the same time it declined for boys. The line is at 1943.

Lynn
babynames %>% 
  filter(name %in% "Lynn") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> lynnplot

lynnplot + geom_vline(xintercept = 1948, color = "navyblue", linetype = "dotted")

Lynn reached peak popularity for girls shortly after it peaked for boys. Lynn declines for boys right as it’s climbing for girls, in the late 1940’s. The line is at 1948.

Meredith
babynames %>% 
  filter(name %in% "Meredith") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> meredithplot

meredithplot + geom_vline(xintercept = 1927, color = "navyblue", linetype = "dotted")

Meredith declined for boys around the same time as it was on its way for a relative maximum for girls, in the mid 1920’s. Meredith for girls has increased and decreased in popularity over the next 90 years, but remained uncommon for boys.

Quinn
babynames %>% 
  filter(name %in% "Quinn") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> quinnplot

quinnplot + geom_vline(xintercept = 2009, color = "navyblue", linetype = "dotted")

Quinn was more popular for boys until 2009 which is when Glee premiered. Quinn increased until 2017 for girls and started decreasing for boys generally in 2009

No Correlation

I found no correlation for most of the names, 15 out of 22.

babynames %>% 
  filter(name %in% c("Allison", "Ashley", "Avery", "Beverly",  "Carol", "Dana", "Darcy", "Lindsay", "Morgan", "Reagan", "Sandy", "Sydney", "Taylor",  "Vivian", "Whitney")) %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() + facet_wrap(~name)

Conclusion of the First Hypothesis

The data disproves the hypothesis that traditionally male names stop being used for boys once used for girls. 15 out of 22 names did not have any correlation. For the seven names that did show a correlation, they point to the idea of a delayed response. The crossover is not immediate, they all take decades until a switch occurs. It would be more accurate to say that when a name that began for boys becomes popular for girls, then it declines for boys. Regarding the 15 names that did not show a correlation, they either started for boys with very low numbers, and remained that way before and after they were introduced and peaked for girls (like Lindsay and Ashley), or they peaked simultaneously but more so for girls (like Dana and Taylor).

Second Hypothesis

The six names that https://www.parents.com gave a reason for are Blair, Morgan, Quinn, Reagan, Taylor, and Whitney.

Blair

The reason: Blair from Facts of Life.
The annotation is when Facts of Life premiered in 1979.
babynames %>% 
  filter(name %in% "Blair") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> blairplot

blairplot + geom_vline(xintercept = 1979, color = "navyblue", linetype = "dotted") +
   annotate("text", x = 1977 , y = 510, label = "Facts of Life", angle = 90)

Morgan

The reason: Morgan Fairchild
The annotation is when The Seduction came out in 1982. This is the chronologically-first movie that IMDB claims Fairchild is “known for.”
babynames %>% 
  filter(name %in% "Morgan") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> morganplot


morganplot + geom_vline(xintercept = 1982, color = "navyblue", linetype = "dotted") +
  annotate("text", x = 1980 , y = 3200, label = "The Seduction", angle = 90)

Quinn

The reason: Quinn from Glee.
The annotation is when Glee premiered in 2009.
babynames %>% 
  filter(name %in% "Quinn") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> quinnplot

quinnplot + geom_vline(xintercept = 2009, color = "navyblue", linetype = "dotted") +
  annotate("text", x = 2007, y = 1500, label = "Glee", angle = 90)

Reagan

The reason: Regan from The Exorcist.
The annotation is when The Exorcist came out in 1973. Note: The name is spelled “Reagan” in the article so that was the spelling checked, despite the character’s name being spelled differently.
babynames %>% 
  filter(name %in% "Reagan") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> reaganplot

reaganplot + geom_vline(xintercept = 1973, color = "navyblue", linetype = "dotted") +
 annotate("text", x = 1971, y = 500, label = "The Exorcist", angle = 90)

Taylor

The reason: Taylor Swift
The annotation is at 2006 because that is when Taylor Swift’s first album was released.
babynames %>% 
  filter(name %in% "Taylor") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> taylorplot

taylorplot + geom_vline(xintercept = 2006, color = "navyblue", linetype = "dotted") +
 annotate("text", x = 2004, y = 12000, label = "Album", angle = 90)

Whitney

The reason: Whitney Houston
The annotation is at 1985 because that is when Whitney Houston’s first album was released.
babynames %>% 
  filter(name %in% "Whitney") %>% 
  ggplot(aes(year, n, colour = sex)) + geom_line() -> whitneyplot

whitneyplot + geom_vline(xintercept = 1985, color = "navyblue", linetype = "dotted") +
  annotate("text", x = 1983, y = 8000, label = "Album", angle = 90)

Conclusion of the Second Hypothesis

The six names do point to an affirmation of the hypothesis that a female celebrity or TV/Film character with a traditionally male name will solidify the name as female. Blair and Quinn crossover at the time of their respective premieres. As does Morgan when Morgan Fairchild enters the public eye. Reagan becomes more used for girls than boys at the same time as its release. Taylor and Whitney are the only two that do not show the correlation, as they were more common for girls than boys much earlier than when their first albums were released respectively. While the hypothesis is not about being named after celebrities, it is worth noting that Whitney reaches peak popularity boys and girls during Whitney Houston’s rise to fame, though much more common for girls than boys. There is no correlation of Taylor Swift’s fame and the naming conventions for Taylor. Taylor reached its height for boys and girls more than 10 years before Taylor Swift released her first album and is generally declining for both since that maximum.