Improve phase of Six Sigma is about identifying actionables around the significant or vital factors found and then prioritizing them, which one to implement first and which one to implement at a later stage. Improve phase also talks about creating a control plan around the action items identified, what will be the back up plan in case the activity fail, who will do it, by when will it be done.
Assuming that the action items have been identified and well implemented, how does it signify that the project goal has also been achieved. It becomes imperative to do statistical comparisons to showcase the before and after analysis. It is very important to show the improvements to the stakeholders statistically. You can use tools like, 2 Proportion, 2 Variance, 2 Sample T, Mann Whitney and others.
This post on Slideshare by Advance Innovation Group will help you understand the importance and usage of such statistical tools.
You may also visit our blog for more videos, articles, documents on the developing better understanding on Improve Phase Deliverables. Visit our website www.advanceinnovationgroup.com to access the blog, or follow this link http://advanceinnovationgroup.com/blog.