(A) Distribution and predicted scores for sgRNAs targeting essential genes. (Top) Predicted activity scores for sgRNAs from Evers et al., 2016 or hCRISPRi-v2 targeting essential genes as defined by Evers et al. (Evers et al., 2016), binned in increments of 0.1. (Bottom) sgRNA growth phenotypes of the sgRNAs in the above bins, z-standardized to the distribution of sgRNAs targeting Evers et al. non-essential genes. (B) ROC analysis of sgRNAs from CRISPRi v1 or hCRISPRi-v2 targeting essential and non-essential genes. sgRNAs were ranked by γ, and considered true or false positives if they targeted essential or non-essential genes, respectively, as defined by Evers et al. (C) Volcano plots of gene phenotypes and p-values for growth screens performed with CRISPRi v1 (Gilbert et al., 2014) and hCRISPRi-v2. For each screen, genes phenotypes were calculated by averaging the growth phenotype (γ) of the 3 sgRNAs with the strongest γ by absolute value, and gene p-values were calculated by performing the Mann-Whitney test comparing all sgRNAs targeting the gene to the full set of negative control sgRNAs. For genes with multiple TSSs targeted, sgRNAs were grouped by TSS and the TSS with the lowest p-value was used for downstream analysis. A comparable number of negative control (NC) genes were generated by randomly sampling 10 non-targeting sgRNAs (with replacement) and analyzed as true genes. Empirically derived thresholds (dashed lines) were calculated as shown, using the NC gene distribution to derive the background standard deviation for z-score. (D) Precision-recall analysis of essential gene screens performed in K562. Statistical precision and recall of essential and non-essential gene sets (Hart et al., 2014) were calculated for genes ranked by growth phenotype in K562. For both CRISPRi and CRISPR nuclease screens (Wang et al., 2015), gene-level phenotypes were calculated as the average log2 fold-change of all sgRNAs targeting the gene (termed CRISPR Scores in ref. [Wang et al., 2015]). (E) Boxplots of CRISPRi and CRISPR nuclease sgRNA phenotypes for several gene sets. sgRNA γ scores (CRISPRi) or log2 enrichments (nuclease) were z-standardized to the corresponding negative control set. Boxplots display the distribution of the negative control sgRNAs or sgRNAs targeting genes on Y chromosome (excluding pseudo-autosomal genes), within the BCR amplicon, or in the gold standard essential sets used in (D). Individual phenotypes for sgRNAs targeting BCR are overlaid with the corresponding boxplot.