Aspects of the present invention provide solutions for projecting slack in an integrated circuit. A statistical static timing analysis (SSTA) is computed to get a set of Gaussian distributions over a plurality of variation sources in the integrated circuit. Based on the Gaussian distributions, a truncated subset and a remainder subset of the Gaussian distributions are identified. Then data factors that represent a ratio between the remainder subset and the truncated subset are obtained. These data factors are applied to the SSTA to root sum square (RSS) project the slack for the integrated circuit that takes into account the absence of the truncated subset.