BIOL3044 Lecture Notes - Lecture 4: Negative Number, Allele Frequency, Squared Deviations From The Mean
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We measure a trait by its deviation, not its absolute value: whatever we"re measuring the deviation from, the reference point becomes zero . Reference point used to define allelic effects are different than that used to define variances: the deviation for allelic effects is the midpoint (halfway from aa homozygote and aa homozygote) When we calculate variances, the reference point used is the average. If we add across the frequency x effect" row, we get the phenotypic average. It is the difference in the allele frequencies, times the allelic effect this is a random mating population with no dominance: recommend remembering (p - q) . If p is bigger than q, the average would be positive. If p is less than q, the average would be negative. Example: when a is common and a is rare. We calculate the average to be -0. 6 , where = 1 (in this example)
