Nat. Biotechnol. 23, 995–1001 (2005), published online 17 July 2005; corrected after print 25 July 2006

In the Methods section, p. 1,000, col. 2, paragraph 2, the text beginning: “The whole plate was discarded if for any time point...” and ending, “The final data set contained 2,431 sequences.” inaccurately described the procedure. The text should read: “Data points for 2,675 siRNAs were carried forward from successful transfections and for which inhibition to ≤60% of residual levels by the positive control siRNA was reached at any time point on either plate, compared to the negative control. Subsequently, 9% of this data was discarded because data points showed a standard deviation of ≥30%. The final data set contained 2,431 sequences with Pearson coefficients of correlation of ≥0.7 between duplicate plates. The data points for each siRNA were averaged and used for neural net training and testing. Inhibition data before normalization will be made available on request to the authors.” This correction does not alter any of the data, the tables, the figures or the text in the remainder of the publication and supplementary material. The error has been corrected in the PDF versions of the article.