est.rf {qtl}R Documentation

Estimate pairwise recombination fractions


Estimate the sex-averaged recombination fraction between all pairs of genetic markers.


est.rf(cross, maxit=4000, tol=1e-4)


cross An object of class cross. See read.cross for details.
maxit Maximum number of iterations for the EM algorithm (not used with backcrosses).
tol Tolerance for determining convergence (not used with backcrosses).


For a backcross, one can simply count recombination events. For an intercross or 4-way cross, a version of the EM algorithm must be used to estimate recombination fractions. (Since, for example, in an intercross individual that is heterozygous at two loci, it is not known whether it shows 0 or 2 recombinations.) Note that, for the 4-way cross, we estimate sex-averaged recombination fractions.


The input cross object is returned with a component, rf, added. This is a matrix of size (tot.mar x tot.mar). The diagonal contains the number of typed meioses per marker, the lower triangle contains the estimated recombination fractions, and the upper triangle contains the LOD scores (testing rf = 0.5).


Karl W Broman,

See Also

plot.rf,, badorder


badorder <- est.rf(badorder)

[Package qtl version 0.98-57 Index]