How do you calculate ROI on Sales Training?

When calculating Sales Training ROI, how do you take the following into consideration?

• Is your sales training linked to business impact within your internal value chain? How?

• How does your measurement leverage connections to the value chain in order to determine impact?

• Do quantitative and qualitative approaches reinforce each other and contribute to a better picture of sales training impact?

• Do you follow recommended processes in order to plan and implement effective sales training measurement?

Any thoughts or ideas / advice would be great!