Hi Gregor the first question is: what type of missing data are you referring to? Phenotypic, markers, of allele calls? I believe there is no right answer for your question because this percentage is relative to the size of your population, number or markers, etc. For instance if you have 80,000 SNPs in your linkage map, and you are missing 10% that is not a big deal. Could you tell us a bit more about the size of your study? Regards.