DY, your comments in this thread and the one you linked expose you as having only the most rudimentary understanding of demography and methematics. For example, if the ratio is 100:105 at birth then it will be fairly similar at age 20. Why would you say it gets much narrower? Death occurs in both genders at a very low rate and even if you were to prove that one gender had a significantly higher death rate it would not be higher by anywhere near 5% of the cohort.
Second, to establish a growth rate for a specific segment of humanity, you need to have a much more sophisticated equation than the one you keep throwing around. Telling me how many children an average family has does not tell me enough about the birth rate but lets leave that alone for now. Assuming you did have enough information to quantify birth rates properly, you have ignored all other variables. The most important ones being death rates, entry from group and exit from group, among others. My understanding is that death rates are not very significant (hey, at least im consistent. You cant ignore death rates in one post and tben say they eliminate 5% of your population in the next post) so lets set that aside too. That bring me to the heart of the matter, which is entry and exit from your segment. And believe me brother, any way you cut it that is a huge, not just significant, factor that cannot be missing from your equation if you want to have any credibility at all. Whether we are discussing baalei tsuva and otd, or migration across sub segment (chassidish girls going out with litvish boys is a big one) or any other element of this factor, the gender makeup of this migration pattern az well as the timing is a major element. Some intellectual honesty. Please.
The avi chai study that nasi folks flaunt sbamelessly is far from reliable. To be blunt, it is crock. Compare the numbers in two separate studies (from different years) and you will see that migration is clouding the data. Otherwise, why isnt the 5th grade population the same as the 2nd grade population from the study 3 years prior? Without migration the number of kids would be the same.
The letter signed by tbe 70 is crock too. They were obviously mislead into signing something that shamelessly made opinion appear like fact. Whatever the intentions of the writers were, that was wrong.
Farkoift v’echol farkoift u’shesay.