Combining Linkage From Different Families Weighted By Information
Content
Kramer, H.H. and C.R. Burnham. 1947. Methods of combining
linkage intensity values from backcross, F2
and F3 genetic data. Genetics 32:379-390.
A weighted mean can be used to combine separate estimates of linkage
intensity to obtain an estimate of the linkage intensity using all the
data. The weights are the total amount of information obtained from
each type of family.
| From
Kramer and Burnham (1947) |
(per
individual) |
| Source
of Data |
Formula
For The Determination of p |
Amount
of Information(i) |
| Repulsion:
Testcross |
p
= (a + d)
a+b+c+d |
1
p(1-p) |
| F2 |
-np +(a-2b-2c-d)p +2d=0 |
2(1+2p)
(1-p)(2+p)
|
The amount of information per individual is derived from:
Where m is the expected proportion for each class and dm/dp is the
first derivative of m with respect to p. I is the total information
content from a given family.
Where n is the total number of individuals per family.
Where Vp is the variance of the estimate of p.
The weighted method of combining different estimates of p from different
types of families is obtained with the following formula:
Combined p value by weighting = 
