Dear Sir or madam, 

I have completed a QLF GLM using edgeR and i have top tags using the script below. I can not get the decideTestsDGE function to work at all and i have read in a few places that it doesn't work with multiple coefficients, is this still the case? It would seem it isn't an issue with the LRT test but i would like to get the number of up and down genes from my QLF test.

Treatment <-factor(targets$treat,levels=c("Sham","Infected"))
Strain <- factor (targets$strain, level=c("D","R"))

y = DGEList(counts=x[,1:8])
keep <- rowSums(cpm(y)>1) >= 4
y <- y[keep, , keep.lib.sizes=FALSE]

y = calcNormFactors (y)
y$samples

design2 <- model.matrix(~Treatment * Strain, data=targets)
design2

y <- estimateGLMCommonDisp(y,design2, verbose=TRUE)
y <- estimateGLMTrendedDisp(y, design2)
y <- estimateGLMTagwiseDisp(y, design2)

fit <- glmQLFit(y, design2)

colnames(design2)

qlf <- glmQLFTest(fit, coef=2:4)
tab <- topTags(qlf)

summary(dt <- decideTestsDGE(qlf))

Error in array(x, c(length(x), 1L), if (!is.null(names(x))) list(names(x),  : 
  'data' must be of a vector type, was 'NULL'

sessionInfo()
R version 3.3.3 (2017-03-06)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.5 LTS

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8    
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8   
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] edgeR_3.16.5  limma_3.30.13

loaded via a namespace (and not attached):
[1] splines_3.3.3   grid_3.3.3      locfit_1.5-9.1  lattice_0.20-35

Many Thanks

Rebecca Pawluk

Well, it should work:

treatment <- factor(rep(c("Sham", "Infected"), each=4))
strain <- factor(rep(rep(c("D", "R"), each=2), 2))
design <- model.matrix(~treatment*strain)
counts <- matrix(rnbinom(100*nrow(design), mu=100, size=10), 
                 ncol=nrow(design))

y <- DGEList(counts)
y <- calcNormFactors(y)
y <- estimateDisp(y, design)
fit <- glmQLFit(y, design)
qlf <- glmQLFTest(fit, coef=2:4)

summary(decideTestsDGE(qlf)) # works fine.

Try to modify the working example above until you generate the error, if you want to demonstrate that there is a bug.