Measuring loyalty program effectiveness

How to measure the loyalty of your customers?
How to estimate your loyalty program effectiveness?
We already mentioned several times the problem of numerical estimations for established loyalty solutions.
Usually it is difficult to see exact numbers not because they are confidential but because the program owners also lack them.
One interesting way to estimate customer loyalty is by using Net Promoter Score (NPS) metric. We recommend to read about it and take a look at real business cases. Having measurable results is an important attribute of well articulated loyalty project and NPS provides a good way to achieve this.