The Likert scale and verbal scale are similar in rating scale they both use words to describe the points on the scale. The American customer satisfaction index uses a 10 point numerical scale which the University of Michigan advocates as the most suitable for measuring satisfaction and for undertaking the subsequent statistical analysis. The most powerful argument in favour of the numerical scale is its suitability when it comes to analysing and communicating the results to colleagues in suppliers’ organisation. On balance the 10-point numerical scale is the most suitable for measuring satisfaction. The verbal scale is probably the easiest to complete, but is far less suitable at the analysis and feedback stage. The SIMALTO scale is ideal for measuring the supplier's adherence to a set of service standards, but that provides a measure of organisational performance rather than a measure of satisfaction.