ANSI 3433 Lecture Notes - Lecture 1: Quantitative Trait Locus, Square Root, Variance
Document Summary
Quantitative trait: phenotypes show continuous numerical expression (not categories) These are typically influenced by many genes (polygenic) most of which are quantitative traits. Value: a measure applied to an individual (not to a population) Population measures: measure applied to a population as opposed to an individual. Animal breeders are concerned with values of animals and also the distributions of and the relationships between values in a population. Results from polygenic inheritance, majority of quantitative traits are normally distributed. For normally-distributed variables, defines the center of the distribution. Describes the shape of the normal distribution. Square root of the population or sample variance. Expressed in the same units as the trait. Approx. the average deviation from the mean. 68% of all observations lie within 1 sd of the mean. 95% lie within two sd of the mean. Covariance: how two traits are values vary together in a population. Correlation coefficient: measure of strength of the relationship between two variables in populations.
