3 Sigma
2 Sigma and 3 Sigma deviation for quality control is explained in https://www.brighthubpm.com/change-management/69495-difference-between-2-sigma-vs-3-sigma-control-charts/
2 Sigma and 3 Sigma deviation for quality control is explained in https://www.brighthubpm.com/change-management/69495-difference-between-2-sigma-vs-3-sigma-control-charts/