Six Sigma in courier services

Six Sigma can help improve courier services that provide transport activities, parcel transport, that means transport and postal activities. Examples of measurable indicators can be: rate of delays in delivery, number or rate of human error, income and expenses on cost centers and cost, fast reaction times.
For example: A Six Sigma project could be "Increase customer satisfaction". The key indicator which give the performance of the process is index of customer satisfaction (S) and it is measured on a scale from 1 to 5, 5 is very satisfied customer.