Grandpa Jason and Grandpa Chad
Grandpa Jason and Grandpa Chad
[A progression chart covering the period of years between 1950 to 1995. One line, representing the birth years of people becoming grandparents, is dotted and begins low at the start, climbs, then steeply declines. Two solid lines, representing the birth years of people named "Chad" or "Jason", begin in the early 1960s, rise almost concurrently, however one declines steadily while the other has a curve almost before the end of the chart. The overlapping area between the dotted and solid lines is shaded. The lines show the following data:]
Birth years of people becoming grandparents this year (United States, very rough estimate) [A dotted line which begins at 1950, rises to its peak at 1970, then steeply declines to zero by the late '70s.]
Birth years of people named "Jason" and "Chad" (Social Security data) [Chad: A solid line beginning at 1962, rises to its peak by 1975, then drops through the '80s and '90s. Jason crosses underneath it in 1985, but then re-crosses it in 1993.] [Jason: A solid line beginning at 1963, rises to its peak between 1977-80, then declines, dropping beneath Chad around 1985 but climbing above it again in 1993.]
[Caption below the comic:] Fun fact: We have now entered the era of "Grandpa Jason" and "Grandpa Chad."

This is another comic with one of Randall's fun facts .
The comic contains three separate curves, with the x-axis being the date and the y-axis being the frequency of three separate sets of data:
The graph shows that the names "Jason" and "Chad" were extremely uncommon in the US prior to the 1960's, but then experienced a surge in popularity, peaking in the late 1970's, and falling off thereafter.  There are a couple of interesting effects when certain names become temporarily trendy. It means that those names become closely associated with a particular age cohort, so one can guess a person's age range based solely on their first name, and therefore predict other tendencies associated with age (this is also explored in 1950: Chicken Pox and Name Statistics ).  A side effect of this is that, when this cohort first comes of age, those names enter the public consciousness as being associated with youth, trendiness and irresponsibility. Of course, that cohort continues to age, and eventually becomes the adult cohort, then the senior cohort, but stereotypes are often slow to change. 2165: Millennials is similarly about how a label has outlived the demographic that it was used to describe, while the people described by the label have outgrown the traits that the label entails.
In addition to dealing with with the inertia of our assumptions and stereotype, this comic also continues a long XKCD tradition of pointing out how quickly time is passing, and how slow we often are to realize it. In this case, those of us in Randall's general age range are used to thinking of "Jason" and "Chad" as names for young, trendy, party animals.  The fact that only a small fraction of people with these names are under the age of 30, and a growing number of them are now grandparents (and that trend is likely to increase rapidly in the next few years), forces us to acknowledge that quite a bit of time has passed since we first formed our world views, and that means we've aged, even if we haven't noticed it.
The title text adds a caveat to the assertion, mentioning the lack of any real evidence for the distribution of ages of Grandparents, but tacitly admits that the matter is not sufficiently important to seek any further precision.
Other possible caveats of the data:
The title text ends with the text "No further research is really *needed,*" referencing 2268: Further Research is Needed . This is also a joke in itself. The emphasis on *needed* is an admission that although more research is *possible*, it's simply not warranted, given the fairly trivial nature of the topic.
[A progression chart covering the period of years between 1950 to 1995. One line, representing the birth years of people becoming grandparents, is dotted and begins low at the start, climbs, then steeply declines. Two solid lines, representing the birth years of people named "Chad" or "Jason", begin in the early 1960s, rise almost concurrently, however one declines steadily while the other has a curve almost before the end of the chart. The overlapping area between the dotted and solid lines is shaded. The lines show the following data:]
Birth years of people becoming grandparents this year (United States, very rough estimate) [A dotted line which begins at 1950, rises to its peak at 1970, then steeply declines to zero by the late '70s.]
Birth years of people named "Jason" and "Chad" (Social Security data) [Chad: A solid line beginning at 1962, rises to its peak by 1975, then drops through the '80s and '90s. Jason crosses underneath it in 1985, but then re-crosses it in 1993.] [Jason: A solid line beginning at 1963, rises to its peak between 1977-80, then declines, dropping beneath Chad around 1985 but climbing above it again in 1993.]
[Caption below the comic:] Fun fact: We have now entered the era of "Grandpa Jason" and "Grandpa Chad."
