## March 25, 2011

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"never date a woman younger than half the man's age, plus six (rather than seven) years. (That also means a celebrity woman should never date a man older than twice her age, less six years.)"

Sorry, I think you did the math wrong.
The rule is W >= 1/2 M + 6 (actually 7 but ok)
If you solve this for M you get
2(W-6) = 2W - 12 >= M
While what you say in the text and the upper limit on your graph is 2W - 6 >= M.
If you move the line to 2W - 12 >= M
or really 2W - 14 >= M
then many men are too old for the women they are with. I know because my partner was too young for me when we started (but we are fine now).
Did you plot people when they got together or the age they are currently. Because you know as time goes by we start following the rule when we did not initially. All the best (an old mathematician with a young statistician).

Love the article! I'm curious if there are any patterns between individual income and where you end up on this chart.

Jeff Edmonds is 100% correct and the math error appears to be a common mistake when interpreting the rule. It has shown up here and in a number of posts on the Urban Dictionary entry for "half-your-age-plus-seven"

Some may find it easier to use a factored version when calculating this in their head:
M <= (W-7) x 2.

Imagine shifting the top line on the graph 3 years to the right and you will have what Revolution Analytics intended. It appears that only a few more couples are over the line so the article is still very valid and interesting.

(Over at OneHalfPlusSeven we post notable couples who walk the line of the half-your-age-plus-seven rule.)

Now I know why I have been married three times! All the women I married were way too old!! I always knew it was their fault. Thanks to David and statisitcs my life is saved. Now does anyone know a 27 year old who is single?

It would also be cool to see the expected years together of the various ranges.

I agree never marry a woman half your age,it usually doesn't work.

Technically speaking, as long as two people are not the exact same age, they will one day, or have already, fit this rule perfectly. One easy way to determine when two people will fit this rule is by downloading the iPhone app, "Dating Calc." It can be found on iTunes from this link: http://itunes.apple.com/us/app/dating-calc/id493736462?ls=1&mt=8.

Very interesting and funny... but every relationship has her own rules...

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