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X2
Tests Part III
Contingency X2
Test With Yates Correction
| X2 = |
(| ad-bc| - 1/2N)2N |
| (a+b)(a+c)(c+d)(b+d) |
| X2 = |
(|2000 - 2700| - 112.5)2x 225 |
| (110)(170)(115)(55) |
| = |
(700 - 112.5)2x 225 |
| 1,182,275,000 |
X = 0.66 with 1df; critical X2
= 3.84 for 1df, α = 0.05
Because the calculated X2
is less than the tabulated X2,
then accept Ho: no interaction between factors.
Another way to calculate Contingency X2.
Observed:
| Environment |
Dominant |
Recessive |
Totals |
| 1998 |
80 |
30 |
110 |
| 1997 |
90 |
25 |
115 |
| |
170 |
55 |
225 |
Expected: Use P(A) P(B) = P(A and B) when A and B are independent.
| Environment |
Dominant |
Recessive
|
Relative
Frequency |
| 1998 |
110
x 170 x 225
(225)2 |
110
x 55 x 225
(225)2 |
110
225 |
| 1997 |
115
x 170 x 225
(225)2 |
55
x 115 x 225
(225)2 |
115
225 |
| |
170
225 |
55
225 |
225 |
| |
Dominant |
Recessive |
| 1998 |
83.17 |
26.85 |
| 1997 |
86.92 |
28.05 |
Copyright
2000©, Ted Helms |
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