**30**wrote:

Hi there, I have 6 microarray data sets that I think FDR<0.05 and fold change >1.5 and <-1.5 for up- and dw-regulated genes respectively are the best (based on Mark R Dalman et al paper) but after normalization with R packages, we have log transformation of fold changes and I know if log FC is 2 it means 4 fold change for gene expression. and logFC -1= FC 0.5. it means, we don't have negative measure for fold change in statistic but have in biology. what is the similar value of FC -1.5 for log FC? (?logFC=FC-1.5)

Thanks in advance

So if log2FC = log2(FC), to get the FC you have to do FC = 2^log2(FC). So if your log2FC is -1.5 you have to compute 2^-1.5

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