We designed a survey on software engineering excellence (SEE) and administered it in 2005, 2006 and 2007 with the Japanese Ministry of Economy, Trade and Industry to better understand the mechanism of how software engineering capabilities relate to IT vendors’ business performance and business environment. We measured the SEE survey results with regard to seven factors: deliverables, project management, quality assurance, process improvement, research and development, human development, and contact with customers. In this paper, we integrated 233 valid responses to the SEE surveys received over three years into a new database and identified 151 unique IT firms. We conducted panel analyses of the seven SEE factors using the three years of data to clarify what influence SEE factors have within a year, year-to-year, and mid-term. Based on the results of the panel analysis, our first observation is that most SEE factors for a year had significant positive influences on the same factors the next year. Second, there were three paths to improving the level of deliverables through project management, quality assurance and research and development in a year. Third, some SEE factors had significant positive influence on different SEE factors in the following year. Fourth, there were some negative paths, implying that effort put toward a particular factor did not pay off during the duration of our research. These efforts, however, might be expected to have longer-term effects on other SEE factors.