Exam 3 Flashcards
Population measure
Any measure applied to a population as opposed to an individual
Population parameter
A true population measure (as opposed to an estimated). Ex. Means, variances, and standard deviation; true correlations between traits
Sample statistic
An estimate of a populations parameter
Normal distribution
A statistical distribution that appears graphically as a symmetric, bell-shaped curve.
Mean
The arithmetic average
Variation
Differences among individuals within a population
Variance
(o^2)
A mathematical measure of variation
Standard deviation
(o)
A mathematical measure of variation that can be thought of as an average deviation from the mean. The square root of the variation
Variable
Any quantity that can take on different numerical values. All elements (except Mu) of the genetic model for quantitative traits are considered variables
Covariation
How two traits or values vary together in a population
Covariance
cov(X,Y)
The basic measure of covariation
Correlation coefficient
r
(x,y)
A measure of the strength of a relationship between two variables
Phenotypic correlation
r
(Px,Py)
A measure of the strength of the relationship between performance in one trait and performance in another trait
Genetic correlation
r
(BVx,BVy)
A measure of the strength of the relationship between breeding values for one trait and breeding values for another trait
Environmental correlation
r
(Ex,Ey)
A measure of the strength of the relationship between environmental effects on one trait and environmental effects on another trait
Regression coefficient
b
(y*x)
The expected or average change in one variable (Y) per unit change in another (X)
True value
An unknown, underlying attribute that affects animal performance. Examples include breeding value, progeny difference, gene combination value, producing ability, and environmental effects