recombination rate

[Stephen P. Daiger]

The actual recombination rate is the number of observed recombination 
events divided by the total number of events.  Like flipping a coin, the 
number of observed recombination events can be larger than 50%.  That is, 
the recombination fraction is a statistical measure; the 50% 
recombination value for unlinked markers is the EXPECTED value which, in 
an actual experiment, may be more or less than 1/2.  In linkage 
computations, some programs will not allow a value of greater than 50% 
for the calculated recombination fraction.  Other programs will allow 
such a value, but a value greater than 50% usually implies an error in 
the data set.