Power studies when a threshold is used to dichotomize a continuous trait

在对高血压或肥胖等性状的研究中，当使用任意准则对一个连续变量进行二分以确定？感情状况？使用计算机模拟评估了这种信息损失对连锁和关联的模型独立检验的功效的影响。基因组分析模拟程序（G. A. S. P.）用于模拟连续变量，阈值设定为约5%的人群将受到影响。选取了100个核心家庭，每个家庭有4个子女，每个家庭至少有2个子女。考虑的模型包括：遗传力从0到0.8，完整和无连锁不平衡，重组分数从0到10厘米。本文比较了离散性状的H-E同胞对测验和TDT测验的四个变异与连续性状的H-E测验的功效。H-E检验对一致性影响对的功效与H-E检验对连续性状的功效几乎相同。当存在完全连锁不平衡时，对于连续性状，关联的TDT检验比H-E检验更有效;其他检验的效力仅略优于I型错误率-G. A. S. P.，遗传计量学，连锁分析，离散，连续，定量，计算机模拟

In studies of traits like hypertension or obesity, information can be lost when arbitary cirteria are used to dichotomize a continous variable to determine ?affection status.? The effect of this loss of information on the power of model-independent tests of linkage and association was evaluated using computer simulation. The Genometric Analysis Simulation Program (G.A.S.P.) was used to simulate a continuous variable with a threshold set to that approximately 5% of the population would be affected. One hundred nuclear families, each with four offspring, were acertained so that at least two offspring were afected in each family. Models considered include: heritabilities from 0 to 0.8, complete and no linkage disequilibrium, and recombination fractions from 0 to 10 cM. The power of four variations of the Haseman-Elston (H-E) sib-pair test for discrete traits and the TDT test were compared to the H-E test for a continous trait. The power of the H-E testfor concordantly affected pairs (only) was nearly identical to that of the H-E test for the continuous trait. The TDT test of association was more powerful than the H-E test for continuous traits when there was complete linkage disequilibrium; other the power of this test was only marginally better than the type I error rate - G.A.S.P., genometrics, linkage analysis, discrete, continuous, quantitative, computer simulation