Now you usually do get it from the Salisbury Family Generator. However, thanks to Thijs asking me if I could code it easily, that is what I did.

The assumptions:
a) The Father is constantly married, from 21 to however old he needs to be. (So if he is 21 when he marries and aging comes before the childbirth roll, he is 22 when the first child can be born.)
b) His wives are young, fertile hotties (Table 1 in Greg's revised childbirth tables), as the previous wives croak quickly (and they do, using those tables, and the one in KAP, another thread to follow).
c) The child survival uses the table in Book of the Estate.

These assumptions come down to about:
Chance of birth: 50% for ordinary / 65% for rich / 75% for superlative
Chance of a son if a child is born: 50%
Chance of the son surviving until 21: about 33%
Total chance of a surviving heir to be born per year: about 8.33% / 10.7% / 12.4%

Crunching the numbers with a computer and random number generator to play the probability dice, I got (unsurprisingly) an exponentally declining curve for the probability of the Father's age. This is simply because the probability stays the same, but the pool of Fathers not yet having a surviving heir shrinking.

Anyway, the differences between the maintenance levels is small in the younger end, and only become larger at the older end. Hence, I am quite happy to simplify it to two dice rolls:
1d6 Father's Age
1-4: 21+1d20/2
5: 31+1d20/2
6: 41+1d20
(If you wish to be nitty-gritty about it , you can give Rich knights -1 year / decade after 20, and Superlative -2 years / decade after 20, but I am not sure I'd bother...)

The fate of the women in the next thread!

Ah, the dangers of putting two knights of math within email-reach of another..

PS: For me: if you are 21 in 485, the childbirth roll takes place in the winter of 485 (so still 21) and at the beginning of 486 adventuring period you turn 22 (with a child of age 1, haven been born in 485). Hence for me the numbers would be one lower... I know I likely miss some months there. But it makes it so much easier for GM to have all winter events 'happen' at 31dec...
Of course nothing stops a GM from having the winter of 485 taking place after the adventure-summer of 484..
[but for me 'first adventure' then 'winter']

fg,
Dr. Thijs

Ah, the dangers of putting two knights of math within email-reach of another..


Well, number-crunching gives occasionally interesting results that must be shared! :)



PS: For me: if you are 21 in 485, the childbirth roll takes place in the winter of 485 (so still 21)


I see where you are coming from, and some of my players do it like that, too. I follow the ordering of the Winter Phase, where you increase your age by 1 in Step 3: Aging, and then go on to Childbirth Rolls in Step 6. It is just a notational thing: the child is born Winter, at the end of 485. At the Winter Phase, at the end of 486, the baby is 1 year old. It matters not if I mark that the baby is born in Jan 486 and then in Jan 487 the baby is 1 year old.

And besides, didn't we have that calendar discussion here in the Play Aids about whether the year starts in March or in January? :P

Based on Greg's reply that his 'target zone' for Child Survival was about 50% (http://nocturnal-media.com/forum/index.php?topic=2417.0), this would skew the Father's age closer to what Superlative would have.

In which case, the table I'd use would be:
1d6 Father's age
1-3 21+1d6
4-5 27+1d20/2
6 37+1d20