Maybe not perfect but I found the 12 questions used by Gallup quite objective in their attempt to link engagement with productivity:
They claim that innovation, entrepreneurship, authentic sales growth, new customers, job growth — all the things that every company needs most — are sparked and inspired by the relationships between managers and employees that these 12 items measure.
I think what is important is to measure the answers before doing anything, identify with the employees maybe 2 or 3 points that impact the most their performance and measure again after changes have been implemented.
Using emotional intelligence can help you succeed as a leader. But what is emotional intelligence, and why is it that success in life sometimes seems unrelated to intelligence and how hard you are prepared to work?