**HW Equilibrium - Equations**

Under conditions of Hardy-Weinberg Equilibrium, the relationships among allelic and genotypic frequencies hold true:

,

, ,

where p= f(A), q= f(a), P= f(AA), H= f(Aa), and Q= f(aa).

The following relationships always hold true:

,

To determine whether or not population is in H-W Equilibrium for a particular locus, one needs to calculate p and q from the genotypic frequencies using:

, ,

If there is a significant difference between the known and calculated genotypic frequencies, then the population is not in H-W Equilibrium. This result implies that one of the five conditions is not met for the locus in question. A **Chi-Square** test is typically used to determine whether or not there is significance between the known and calculated genotypic frequencies. The Chi-Square equation is: