Confidence factors help you estimate the progress of your current project using a scale from 0% to 100%. From this scale, you can determine how successful your tests have been in analyzing a project, and understand what types of tests may still need to be conducted. The higher the confidence factor number, the better your application is working and the more likely it is to succeed after deployment.
Ideally, what you want to see when you use confidence factors during a project is an increase in all statistics as the project matures. These statistics are particularly valuable when integrating and testing various modules into a final product. Confidence factors show you at a glance if any one module that is added to a project is complete enough to stay in the final build or if it needs further work.