This guide from TrainingCheck provides tips on how to evaluate the Kirkpatrick four levels.
Thanks - this was just what I needed!
A really useful and practical summary with some equations to create tangible results.
Just to add a couple of ideas...
For Leadership Development I would add a before and after 360 feedback questionnaire to tracking changes over time (improvements hopefully) as a practical way of assessing Level 3 for interventions that last around 12 months.
In addition, learning logs and work based projects where participants have to evaluate for themselve ROI or improvements against PIs can be collated and used as evaluation against Level 4.