Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Rd., EH9 3JT, Edinburgh, UK.
Theor Appl Genet. 1996 Jan;92(1):130-9. doi: 10.1007/BF00222963.
Deterministic sampling was used to numerically evaluate the expected log-likelihood surfaces of QTL-marker linkage models in large pedigrees with simple structures. By calculating the expected values of likelihoods, questions of power of experimental designs, bias in parameter estimates, approximate lower-bound standard errors of estimates and correlations among estimates, and suitability of statistical models were addressed. Examples illustrated that bracket markers around the QTL approximately halved the standard error of the recombination fraction between the QTL and the marker, although they did not affect the standard error of the QTL's effect, that overestimation of the distance between the markers caused overestimation of the distance between the QTL and marker, that more parameters in the model did not affect the accuracy of parameter estimates, that there was a moderate positive correlation between the estimates of the QTL effect and its recombination distance from the marker, and that selective genotyping did not introduce bias into the estimates of the parameters. The method is suggested as a useful tool for exploring the power and accuracy of QTL linkage experiments, and the value of alternative statistical models, whenever the likelihood of the model can be written explictly.
确定性抽样用于数值评估具有简单结构的大型家系中 QTL-标记连锁模型的期望对数似然曲面。通过计算似然的期望值，可以解决实验设计的功效问题、参数估计的偏差、估计的近似下限标准误差以及估计之间的相关性，以及统计模型的适用性。实例表明，在 QTL 周围使用支架标记大约将 QTL 与标记之间的重组分数的标准误差减半，尽管它们不会影响 QTL 效应的标准误差，标记之间的距离估计过高会导致 QTL 与标记之间的距离估计过高，模型中的更多参数不会影响参数估计的准确性，QTL 效应及其与标记的重组距离之间存在中度正相关，选择性基因分型不会导致参数估计产生偏差。该方法建议作为探索 QTL 连锁实验的功效和准确性的有用工具，以及替代统计模型的价值，只要模型的似然可以明确写出。
