Where the 10% Came From

To Whom It May Concern:

I don’t know if you realize, but that “10% will never marry” statistic has cause quite a flurry of alarm and anger among young spinsters. I’ve been involved in a series of conversations via email, blog posts, and real live talking all about that simple little “10%”.

Mostly we want to know: where on earth did it come from?

Where did the number come from, and how did you conclude that, in fact, 10% of today’s graduating class will never marry?

I thank you for clarifying this point for us.
21, Unmarried, and Not Particularly Worried


Hi [Bad4Shidduchim],

I understand that dealing with this issue is very painful, especially to one who is currently single. However if we don’t deal with it the situation will stay the way it is.

Briefly the 10% is based on two assumptions. The first is that the community is growing by about 4% a year and the second is that boys marry when they are about 3 years older than girls.

In a growing community, there are more younger members than older members. In a community growing at 4% a year there are 104 first graders for every hundred second graders. This means that there are 112 20-year-olds for every 100 23-year-olds (4% a year times 3 years leaving compounding out for simplicity). As more boys than girls are born, this works out to a gap of about 10%.

Much of this also depends on how one defines the target community as there is a large gray area between the various segments of the orthodox community.

I have been researching this area for a few years. I took my data from the Avi Chai Study on day schools. By comparing the sizes of different grades I was able to extrapolate the growth rate of the community. I am an actuary – for all it is worth. There is another far more detailed study done using multiple methods to derive the growth rate and tallying the ratio of boys to girls in shidduchim.

I don’t have any hard numbers for historical growth rates and age gaps. However I do believe that growth rates have been growing (the second derivative of the population) over the past several decades. If this is true, the problem should gradually worsening, assuming the age gap remains the same.

We have been working on this for several years and tried what we could. We could not think of anything else to do other than offer incentives to shadchanim to address the issue. If you have any ideas as to how this issue can be addressed I would love to hear it. I am sure you know that raising money is – to put it mildly – not easy.

I understand the pain this line causes to many people; however given the apathy we have encountered regarding this issue we felt the situation had to be laid out explicitly.

We made the decision. Specifically – R’ Kalman Epstein felt, and still feels, that this is an extremely serious issue and if the only way to deal with it is by scaring people than that is what must be done.

The phrase “10% will never get married” is not meant to be a prediction (certainly not a binding prediction). It was meant to be a warning that something must be done. I sincerely hope that we are wrong; however this is the situation as we see it.

Over the past several weeks we have been seeing signs that people are taking this issue more seriously. An example that comes to mind: two nights ago a shadchan called me and in the course of the conversation mentioned that the boy originally did not want to go out with a girl his own age. After he heard about the program and the importance of the issue he decided to go out.

I don’t know if I answered all of your questions. If not or if you would like anything else please give me a call or email me again.

Kol Tuv
Chaim Tropper



Thanks for the clear explanation. Just one question: why would this be a recent problem? Meaning, haven’t births always increased as time passes? And haven’t men almost always married women younger than them? In which case, wouldn’t there always have been a percentage of the population that never married?




A couple of points.
1) The growth rate was much lower. Women nursed longer and more consistently, causing children to be spaced several years apart. Infant mortality and the childhood mortality rate was much higher, which also contributed to a depressed growth rate.
2) Maternal mortality was also much higher (0.6% per birth if I remember correctly), leaving many men widowed at a relatively young age. Furthermore, over all the mortality rate was higher leaving many widows and widowers.
3) It may have been a problem but people had much bigger problems to deal with such as illness lack of food etc.

I do not know anything about the average historical age gap but it could very well be that it was lower than it is today.

There have been times that the ratio was skewed significantly more than it is today, generally due to war. In fact I believe that after WWI the ratio was 2 to 1 in some places. There was considerable talk about allowing polygamy then.

All the Best,

Chaim Tropper


Thanks again. May I post your response on my blog for the benefit of the masses?


Yes, just make sure there are no typos.

I am attaching an article I wrote with a friend that has a little more on this issue.

Although there are parts of the article I don’t agree with I think you may find it interesting.

The article can be found over here.


Special thanks to Anon Anonymous for her assistance.


10 thoughts on “Where the 10% Came From

  1. Bad4shidduchim,

    While some of the information in Chaim Tropper’s letter and his article is correct, there are some serious flaws that are also present. To point out the errors would take far more room then would be appropriate as a comment here, so I am going to post about it myself.

  2. Well, one basic mathematical error – at a growth rate of 4% per year, after 3 years it would be 112.4864. (since it compounds)
    Don’t think that makes much of a difference to the aergument, but as an actuary I would think he’d get the numbers right.

  3. Hello

    why are you in this self imprisoned ‘shidduch scene” I have neice of is a very attractive young woman of 22 who has been conditioned to act & behave in a cerain manner. So I ask “if a boy smiles your way in shul, would you smile back”? the answer was no

  4. Hey Theo – he explained that he left out compounding.

    Frank – I’d probably smile back, but so what? I’m in the shidduch scene because that’s where all the people I would consider marrying are. If a guy tried to hit off me in shul I’d consider him either a loser or not my type – depending on the circumstances.

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