Short Formulas
X
Short Formula
Short formula for 9:3:3:1
X
= 16(a
+ 3b
+ 3c
+9 d)
- n
9n
The terms a, b, c, d refer to the following observed
numbers:
class A_B_ A_bb aaB_ aabb
observed a b c d
Short formula for testcross data: AaBb x
aabb progeny
X
= (a
+ a
- a
- a
)
for the A locus to test 1:1 ratio
n
X
= (a
- a
+ a
- a)
for the B locus to test 1:1 ratio
n
X
= (a
- a
- a
+ a)
to test for lack of independent assortment
n
The terms a,
a,
a,
a
refer to the following observed numbers for each class.
class AaBb Aabb aaBb aabb
observed a a a a
Short formula for F
data with four classes.
class A_B_ A_bb aaBb aabb
observed a a a a
X2A = (a1
+ a2 - 3a3
- 3a4)2
to test for 3:1 ratio for the A locus
3n
X2B
= (a1
- 3a2 + a3
- 3a4)2
3n
X2L
= (a1
- 3a2 - 3a3
+ 9a4)2
to test for lack of
9n independent
assortment
X2
= 16(a21
+ 3a22
+ 3a23
+ 9a24) - n Ho:9:3:3:1
fit
9n
