Prosci's ADKAR model

http://www.wipro.com/documents/resource-center/Applying_Change_Management_Practices_in_Government_Organizations.pdf

I do not wok for EPA!

Continuity and change using fowling stream strategy

Instead of looking at the whole organization it will be useful to look at the KPIs of the thing that you are changing in the organization.

Check out my recent paper in the International Journal of Project Management. I specifically address the issue of success in projects.

Article The integration of project management and organizational cha...

Above, Muammer mentions KPIs, which points to the measures of success being specific to an organization.  Something I've found helpful is to develop a maturity model that articulates growth towards goal achievement, with KPIs for each level of maturity.  This reframed success in terms of an evolutionary approach rather than an all or nothing approach.  Krishnan mentions ADKAR.  It's a good model but not universal.  I've found it less helpful for transformational change, where the need for change is clear but the end state is not in the early stages of change.   This again links to the concept of evolution.  

The other factor in here is that change is rarely a finite thing, with a nice tidy ending and  an absolute success, or not.  One of my mantras around this is that when you get there, there isn't there any more.  Again, defining change effectiveness in terms of growth seems more helpful than the notion of fixed success.

Ahmad:

There are many ways to measure success in organizational change management.

The success/failure of an organizational change initiative depends upon many factors including the strategies and tactics chosen for change managements. The following paper outlines few important methods to validate such survey questionnaires. 

Take a look...

Article Towards Balancing Multiple Competitiveness Measures for impr...