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Homework Assignment #4
Questions
- Let α = 0.05 and test
Ho: Factors A and B are independent. Use the contingency
X2
test and the short formula to test Ho. Then calculate
the expected frequency for each class and use
| X = |
S(|O-E| - 1/2)2 |
to test Ho. |
| E |
A cross Rr x Rr was made in
both 1997 and 1998. Factor A is the genetic segregation
and factor B is the year. The F2
progeny are expected to segregate in a 3:1 ratio each
year.
| Segregation |
| Year |
Dominant |
Recessive |
| 1997 |
80 |
30 |
| 1998 |
90 |
25 |
Interpret the results of the X2
test.
- Four plants were testcrossed. Each testcross was
the result of crossing an F1
plant to a homozygous tester. The testcross can be
represented using the symbols Rr x
rr
Rr:rr. Use the heterogeneity X2
to determine whether the same segregation ratio was
observed for each of the four plants. Interpret the
results. The following data was observed.
| Classes |
| Plant |
Dominant |
Recessive |
Totals |
| |
| 1 |
27 |
22 |
49 |
| 2 |
40 |
45 |
85 |
| 3 |
51 |
48 |
99 |
| 4 |
15 |
16 |
31 |
| |
| Totals |
133 |
131 |
264 |
| |
|
|
|
X2 |
df |
| 1 |
O |
27 |
22 |
|
|
| |
E |
24.5 |
24.5 |
|
|
| |
(O-E)2 |
0.255 |
0.255 |
0.510 |
1 |
| |
E |
|
|
|
|
| 2 |
0 |
40 |
45 |
|
|
| |
E |
42.5 |
42.5 |
|
|
| |
(O-E)2 |
0.147 |
0.147 |
0.294 |
1 |
| |
E |
|
|
|
|
| 3 |
O |
51 |
48 |
|
|
| |
E |
49.5 |
49.5 |
|
|
| |
(O-E)2 |
0.045 |
0.045 |
0.090 |
1 |
| |
E |
|
|
|
|
| 4 |
O |
15 |
16 |
|
|
| |
E |
15.5 |
15.5 |
|
|
| |
(O-E)2 |
0.016 |
0.016 |
0.032 |
1 |
| |
E |
|
|
0.926 |
4 |
| Total |
O |
133 |
131 |
|
| |
E |
132 |
132 |
|
| |
(O-E)2 |
0.008 |
0.008 |
X2
= 0.016 accept Ho:1:1 |
| |
E |
|
|
|
| |
X2 |
df |
|
| Total |
0.016 |
1 |
|
| Summed |
0.926 |
4 |
|
| Het. |
0.91 |
3 |
accept
Ho: homogenous data |
Copyright
2000©, Ted Helms |
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