Statistically, I would expect half the clutch from a lesser x normal to be lesser and the other half to be normal.
Therefore, a one-egg clutch would be expected to produce half lesser and half normal. Is the lesser half of the baby the front half or the rear half?
The binomial theorem covers distribution of results in a given set of trials. Briefly, the larger the clutch, the lower the probability of getting a exact 50:50 split. A 50:50 split is the most likely single result, though.
The 16 possible results from a 4 egg clutch:
lesser - lesser - lesser - lesser = 4 lesser
lesser - lesser - lesser - normal = 3 lesser
lesser - lesser - normal - lesser = 3 lesser
lesser - lesser - normal - normal = 2 lesser
lesser - normal - lesser - lesser = 3 lesser
lesser - normal - lesser - normal = 2 lesser
lesser - normal - normal - lesser = 2 lesser
lesser - normal - normal - normal = 1 lesser
normal - lesser - lesser - lesser = 3 lesser
normal - lesser - lesser - normal = 2 lesser
normal - lesser - normal - lesser = 2 lesser
normal - lesser - normal - normal = 1 lesser
normal - normal - lesser - lesser = 2 lesser
normal - normal - lesser - normal = 1 lesser
normal - normal - normal - lesser = 1 lesser
normal - normal - normal - normal = 0 lesser
Probability of a 4 lesser clutch = 1/16
Probability of a 3 lesser clutch = 4/16
Probability of a 2 lesser clutch = 6/16
Probability of a 1 lesser clutch = 4/16
Probability of a 0 lesser clutch = 1/16
This shows that while the probability of a lesser from one egg is 1/2, the probability of 2 lessers from a four egg clutch is less than 1/2. This is why the odds are on a per egg basis rather than a per clutch basis.
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