Nat. Methods; doi:10.1038/nmeth.2645; corrected after print 11 October 2013

In the version of this article initially published online, the dilution for the ERCC Spike-In Control Mix added to the lysis mix was given as 1:40,000 in the Online Methods. The actual dilution used was 1:400. The error has been corrected for the PDF and HTML versions of this article.