John graduated with a degree in industrial engineering and in 2008 accepted a position at a company where he was doing estimates for the manufacturing division. In 2013, John was promoted to project engineer and was responsible for the coordination of all estimates by all of the divisions. At the beginning of this year, he was transferred to small program project management. For five projects, John was "right on the money." However, this last project proved that he was over by $20,000. A meeting was called to discuss why the overrun occurred. Paul is worried and wonders what he should say in his defense. What are your thoughts on what he should say?