The quality checklist was tested and refined on the Koch Mid-Plants Project in Corpus Christi, Texas during 1993–4. Piping foremen were divided into two groups, those with PPP 50%.The productivity of the 2nd group was 30 points higher than the 1st group … if the first group was performing at 15% over budget, the second group was performing at 15% under budget’ (Ballard and Howell, 1994b).