I know it's supposed to be 50/50....

[walkswithdog]

So far this year I'm approaching 70% roo over about an 80 chick sample

so I'm hatching more because my PULLETS should start happening any time now RIGHT????

Really gravely ticked at my odds this year. Oh well, there's always next year, and I have a new flock of layers so hopefully we've dumped the boy laying fiends.

 

[Marbleheader.]

Quote:
Here are the odds, assuming each chick has an equal chance of being male or female.

12 chicks means 4096 possible combinations (12 male, 0 female; 11 male; 1 female; 10 male, 2 female, etc.)

The formula for calculating the numbers of each pair is:

(Total chicks)! / (M! X F!). "!" is the factorial function.
This yields the following results

12 M / 0 F = 1
11 M / 1 F = 12
10 M / 2 F = 66
9 M / 3 F = 220
8 M / 4 F = 495
7 M / 5 F = 792
6 M / 6 F = 924
5 M / 7 F = 792
4 M / 8 F = 495
3 M / 9 F = 220
2 M / 10 F = 66
1 M / 11 F = 12
0 M / 12 F = 1
TOTAL = 4096

So the odds of getting exactly 6 of each is 924 / 4096 = 22.5 percent
So the odds of NOT getting exactly 6 of each is 77.5 percent -- pretty high.


Of course, getting 6 of each is by far the most likely outcome and the probability of getting at least 5 of each (i.e. 7 M / 5F; 6 M / 6F; or 5 M / 7F) is more than 60 percent: (792 + 924 +792) / 4096 = 61%


OK, sorry for the nerd rant!

 

[speckledhen]

Usually, the odds depends on larger samples, as NY said. However, this past year, I did get an even number of male and female Welsummers from 12 birds. Have never had an all-male hatch, but did come close a couple times.
It's usually 60/40 with 60 being male for me, if I'm lucky. I've never incubated huge batches of one breed to test the odds, though.