Nat. Methods 11, 33–38 (2014); published online 30 December 2013; corrected after print 13 January 2014

In the version of this article initially published, the text stated that Toby Jenkins directs liquid handling for instrument manufacturer TTP Labtech. This name was misspelled; the correct name is Joby Jenkins. The error has been corrected in the HTML and PDF versions of the article.