What’s the Significance of Your Sign? A Guest Post

A reader named E. Allyn Smith, a Ph.D. student in linguistics at Ohio State University, wrote in with the following observations.

I’ve been thinking about birthdays a lot lately, because November 15th to the 27th is one of the annual “birthday rushes” in which I have eight birthdays in two weeks. It got me thinking that not only are there a lot of birthdays in that short period of time, but two of the days in that interim have more than one birthday. It reminded me of the birthday problem in mathematics (see more about this here) in which, once you have 23 people in a room, there’s a larger than 50 percent probability that two of them will have the same birthday.

In a similar vein, I became curious about a variety of properties of the birthdays I keep track of in my calendar. Here are some facts that I found (if I don’t have your birthday, feel free to leave it in the comments section “in the name of science”):

Total number of birthdays on my calendar: 51
Number of weeks in a year: 52

Of those weeks in a year, here’s the breakdown of how many birthdays I have in a given week (obviously this changes year to year, but not significantly):

0 people – 22 weeks
1 person – 15 weeks
2 people – 11 weeks
3 people – 2 weeks
4 people – 2 weeks

Number of days with more than one birthday: 5
Greatest number of birthdays in a two-week period: 8
Greatest number of consecutive weeks with no birthdays: 6

Upon discovering that so many weeks had no birthdays (in addition to the six-week stretch, there were also periods of four and three weeks at a time with no birthdays), I thought back to the horoscopes in magazines like Seventeen, in which they list your personality on the basis of your zodiac sign, as well as the compatibility (or lack thereof) between different signs. So I decided to see whether the birthday-dense times in my calendar correlated with my “compatible” zodiac signs, while the birthday-sparse periods correlated with my “non-compatible” zodiac signs.

The first thing I noticed was that my two “rush times” don’t fall into individual “signs” (for example, Nov. 15 to 27 spans both Scorpio and Sagittarius), but the next thing I noticed is that I’m supposedly not compatible with either of those signs. Let me point out that this group includes my college roommate (and we all know that you’d have to be pretty compatible to choose to live with someone in a dormitory room for a second consecutive year) as well as my brother. Meanwhile, the six-week no-birthday period extends from the last three weeks of Pisces through the first three weeks of Aries. Even in the weeks on either side, I only have one birthday, but I supposedly am compatible with Aries and Pisces.

Conclusion: either 1) zodiac “compatibility” is bunk (my personal favorite); or 2) I’ve managed to make friends primarily with those I’m not compatible with while simultaneously avoiding people with which I would be compatible. I reserve the right to do further research on this topic.

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  1. Marc P says:

    If this were a movie, I’d refer to it as a “chick flick”.

    Women who know me, upon learning that I’m a Cancer, always tend to respond, “You are soooooo Cancer.” Far out…

    For what it’s worth, have you found correlations between birthdays and holidays. My mother shot for the 4th of July, twice!, and narrowly missed. My brother and I have birthdays three days apart, July 8 and July 11, respectively. A fiend of mine, however, nailed it.

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  2. Marc P says:

    If this were a movie, I’d refer to it as a “chick flick”.

    Women who know me, upon learning that I’m a Cancer, always tend to respond, “You are soooooo Cancer.” Far out…

    For what it’s worth, have you found correlations between birthdays and holidays. My mother shot for the 4th of July, twice!, and narrowly missed. My brother and I have birthdays three days apart, July 8 and July 11, respectively. A fiend of mine, however, nailed it.

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  3. discordian says:

    3 other people where I work share my birthday – 7/11
    there are about 100 people in this facility, so that’s 1/25.

    make of it what you will

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  4. discordian says:

    3 other people where I work share my birthday – 7/11
    there are about 100 people in this facility, so that’s 1/25.

    make of it what you will

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  5. Marc P says:

    Reading discordian’s post jarred my memory. In keeping with my original theme (#1), a few years back, my department briefly consisted of 13 employees. Three of us (self include) were born on July 11 or 12. Additionally, one of my best childhood friends was born on July 3…

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  6. Marc P says:

    Reading discordian’s post jarred my memory. In keeping with my original theme (#1), a few years back, my department briefly consisted of 13 employees. Three of us (self include) were born on July 11 or 12. Additionally, one of my best childhood friends was born on July 3…

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  7. A says:

    I tend to have the exact same two week rush in November. I like to attribute it to Valentine’s day. Same thing with the end of August and Begining of September – Christmas and New Year’s babies. So the Birthday rush may just be the work of probability. If there are more babies born around a certain time, I’d expect to know more people with those birthdays.

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  8. A says:

    I tend to have the exact same two week rush in November. I like to attribute it to Valentine’s day. Same thing with the end of August and Begining of September – Christmas and New Year’s babies. So the Birthday rush may just be the work of probability. If there are more babies born around a certain time, I’d expect to know more people with those birthdays.

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