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, 10:27, 2 February 2015
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| = Derivation for counting the number of genotypes = | | = Derivation for counting the number of genotypes = |
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− | For the case where A < P, there must always be P observed alleles and there can only be at most A alleles. This can be modeled by P+A-1 points where you choose A-1 points to be dividers to define the alleles.
| + | There must always be P observed alleles and there can only be at most A alleles. This can be modeled by P+A-1 points where you choose A-1 points to be dividers that separate the alleles. |
| Thus the number of ways you can observe this is <math> \binom{P+A-1}{A-1} </math>. | | Thus the number of ways you can observe this is <math> \binom{P+A-1}{A-1} </math>. |
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− | For the case where A >= P,
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− | <math>
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− | \begin{align}
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− | F(P,A) &= \sum_{i=1}^{P} \| \{\text{i distinct alleles observed in a set of P alleles}\} \| \\
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− | &= \sum_{i=1}^{P-1} \| \{\text{i distinct alleles observed in a set of P alleles}\} \| + \| \{\text{P distinct alleles observed in a set of P alleles}\} \| \\
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− | &= \sum_{i=1}^{P-1} \| \{\text{i distinct alleles observed in a set of P alleles}\} \| + \binom{A}{P}\\
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− | &= \sum_{i=1}^{P-1} \| \{\text{ways to choose i distinct alleles}\} \|\| \{\text{ways to arrange i distinct alleles in a set of P alleles}\} \| +\binom{A}{P} \\
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− | &= \sum_{i=1}^{P-1} \binom{A}{i}\binom{P-1}{i-1} + \binom{A}{P}
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− | \end{align}
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− | </math>
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| = Derivation for getting the index of a genotype in an enumerated list = | | = Derivation for getting the index of a genotype in an enumerated list = |