我们在生物数据统计分析中,经常会听到p-value,adjusted p-value,q-value以及False discovery rate(FDR)。比如最常见实验组和对照组的差异基因表达分析,除了获得一个p值(p-value),通常而言还会得到一个adjusted p-value或者FDR(false discovery rate)。那么他们之间到底有什么关系,为什么已经有了一个p-value来指征显...
虽然p-value直观地表示在假设H0（不存在差异）为真时，观察到数据的概率，但它可能受到多重假设检验的影响，导致假阳性结果。为了解决这个问题，我们引入了调整后的p-value（如adjusted p-value或q-value）和FDR，它们旨在控制假发现的数量。调整后的p-value，如q-value，是FDR的计算结果，它考虑了所有...
1) P-value 是 (在H0 = true的情况下)得到和试验数据一样极端(或更极端)的统计量的概率. 它不是H1发生的概率. 假定吃苹果的一组和不吃苹果的一组的差异为D, P-value=0.2的意思是, pure randomly (即H0=true)的情况下, 观察到和D一样或比D更大的差异的概率是20%. 2) p-value 的本质是控制PFR ...
p-value:表示某个基因在分组之间的表达是否差异显著,一般认为p-value<0.05为显著。adjusted p-value:即经过统计学方法校正后的p-value,由于统计学上常用的校正方法包括“BH”、“FDR”等,所以在一些文章中,我们也会看到筛选差异基因的阈值是FDR<0.05。p值越小差异越显著,但直接用adjusted p-value画图的话点会...
adjusted p-values". The adjusted p-value definition that you give is essentially the same as the BH adjusted p-value, except that you omitted the last step in the procedure. Your definition as it stands is not an increasing function of ...
简单说来,为了控制假阳性,无论是RNA-seq,还是CHIP-seq,还是GWAS的单次检验得到的P value都要经历多重检验校正后,变为adjusted p_value 或 FDR才可以用。而这样的处理会导致假阴性急剧上升。校正后,我们经常会面临的就是我们所关心的目标基因显著性信号不够强的问题。面对大量大于0.5%的FDR数据,我们该如何处理。
The critical value is determined based on the desired false discovery rate (FDR) control.Here are the steps involved in calculating adjusted p-values using the Benjamini-Hochberg procedure:Sort the p-values in ascending order. Assign a rank or position (denoted as “i”) to each p-value ...
sum(p.adjust(pvals,method="BH")<0.05)#13 从图中看到的一样 代码语言:javascript 复制 adj.pvals<-p.adjust(pvals,method="fdr")compare_list<-data.frame(org.pvalue=pvals[order(pvals)][1:13],adj.pvalue=adj.pvals[order(adj.pvals)][1:13])#p_adjusted(i)=p(i)*(m/i)i<-seq(1:13)...
In all, 972 CpG sites were significantly hypermethylated while 209 sites were hypomethylated in prostate tumor tissue (FDR adjusted p-value < 0.05; fold ... JK Sun,WK Kelly,A Fu,... - 《Cancer Letters》 被引量: 91发表: 2011年 Gene expression responses in human lung fibroblasts exposed to...
(imagine the projector wasn't working), the probability of seeing so much asa single voxel above statistical threshold should be 0.05. There is obviously an arbitrary elementto this, and it's open to debate how quickly research would progress if this standard were adjusted.At least one of ...