In its first known appearances (in the book Her Royal Highness Woman by Max O'Rell, "The little shepherd of Kingdom Come" by John Fox, and the 1951 play The Moon is Blue by F.
Hugh Herbert), it's stated or implied that at the beginning of a relationship or marriage, the woman's age "is supposed to be half the man's age, plus seven", which gives a different (asymmetrical) interpretation to the rule.
The “half your age plus seven” rule of thumb probably helps you avoid being a creep, but is it accurate?
Much to my surprise, when overlaying a line representing the rule of thumb on Kenrick and Keefe’s results (see red line in the figure below), you can see it closely matches the low end of the range (i.e., youngest preferred) for all but the oldest men.
As you can see, the comic mentions some analysis involving census bureau data and dating pools.
Our goal in this post is to replicate the analysis that leads to these curves.
This blog is my labor of love, and I've spent hundreds of hours working on the projects that you'll read about here.
(And people only slightly older than 14 should only be involved with those almost exactly the same age as themselves.) To read the chart, go to the position along the x-axis which corresponds to your age, and the green range (between the black and red lines) directly above that position corresponds to the range of your partner's ages which is deemed acceptable by the rule.
(And now we see why the last panel of the XKCD comic above applies so well to me…) Sure enough, if we overlay Rudder’s Ok Cupid data over the first chart, we see that men follow the rule almost exactly.
There are a few spots in the mid-30’s where men seem willing to dip ever so slightly past the safe zone of non-creepiness, but that trend quickly ends by their 40’s.
Formally, we can denote these two bounds as: Still more mathematically, if we denote the creepiness rule by $f$, upper and lower bounds by $\text$ and $\text$ and your age by $x$ then we have: $$\text = f(x)$$$$f(\text) = x \Leftrightarrow \text = f^(x)$$This can be easily implemented, as the inverse creepiness rule is "you can't date people older than twice (your age minus 7 years)".
As one can see from the plot above, the dating interval is getting larger with your age.