This excerpted from The Jewish Press’ website:
All In The Numbers: A Mathematical Explanation For The ‘Shidduch Crisis’
Ariel Halpert, Ph.D.
Posted Jan 23 2008
Data from the U.S. Census of 2000 provides supporting evidence that our community is growing in size. From the mid-1970’s to the early 1980’s, the number of children within the New York frum community born in a given year as compared with the number born in the previous year increased by just under 1% per year. So for example, if 10,000 children were born in 1975, then approximately 10,100 were born in 1976. Then, from the early to mid-1980s, this rate increased to nearly 1.5%, and by the mid-1980’s the rate was over 2%. These numbers may not sound like much, but when viewed within a demographic model, the results can be significant.
Using the above numbers along with a simple demographic model, and assuming that the age gap between husbands and their wives averages around 3 years (with a range of 1 to 5 years), we can estimate ratios of single men to single women who are 1 to 5 years younger than them.
For single women age 20, the modeled ratio is approximately 90%, which means that for every 100 single women at age 20, there are only about 90 single men who are 1 to 5 years older in the pool of potential marriage candidates. For single women age 25, the modeled ratio is only around 80%, and for single women age 30, the modeled ratio drops to around 60%.
(His Ph.D is in mathematics.)