X2 Tests For F2 Data
Test
Ho:9:3:3:1 ratio overall w/3 df
Ho:3:1 ratio for A locus w/1df
Ho:3:1 ratio for B locus w/1df
Ho:A and B are independent w/1df
Ho:homogeneity X
for each X
above
Example: F
test for linkage
| Family |
A_B_ |
A_bb |
aaB_ |
aabb |
Total |
| 1 |
47 |
8 |
11 |
9 |
75 |
| 2 |
75 |
14 |
14 |
11 |
114 |
| 3 |
65 |
13 |
12 |
11 |
101 |
| Totals |
187 |
35 |
37 |
31 |
290 |
For totals: Ho:9:3:3:1
X
= (a
+ a
- 3a
- 3a
)
3n
= [187 + 35 -3(37)
- 3(31)]
3(290)
= 324 = 0.372
w/1df accept Ho:3:1
870
X
= (a
- 3a
+ a
- 3a)
3n
= (187 - 105 + 37
- 93)
870
= 676 = 0.777
w/1df accept Ho:3:1
870
|
X2L
= (a1 - 3a2
- 3a3 + 9a4)
9n
= (187
- 105 - 111 + 279)
2610
= 62500
= 23.946 w/1df reject Ho: independence
2610 between
loci
|
