Calculating Customer Satisfaction Index (CSI)

The Customer Satisfaction Index represents the overall satisfaction level of that customer as one number, usually as a percentage. Plotting this Satisfaction Index of the customer against a time scale shows exactly how well the supplier is accomplishing the task of customer satisfaction over a period of time.
Since the survey feedback comes from many respondents in one organization, the bias due to individual perception needs to be accounted for.
This can be achieved by calculating the Satisfaction Index using an importance weighting based on an average of 1.
Calculate the average of all the weightings given by the customer. Divide the individual weightings by this average to arrive at the weighting on the basis of average of 1. Customer's higher priorities are weighted more than 1 and lower priorities less than 1. The average of the Customers Importance Scores are calculated and each individual score is expressed as a factor of that average. To understand the calculations consider following example:
The following table shows the Weightings & Scores assigned on a scale of 1 - 10 by the Customer.

 
Parameter(P)      Weighting (A )                Score( B)Weighting (avg. of 1)    C Weighting (avg. of 1) * Score D = B *C

P1                         7                                                8                                               1.17                              9.24

P2                        5                                                4                                                 0.83                             3.33

P3                        9                                                8                                                 1.50                             12.00

P4                       3                                                 3                                                 0.50                               1.50

P5                      6                                                  4                                                  1.00                              4.00

        Average = 6.00                              Average = 5.40                                                                           CSI = 6.01




A = Average Weighting assigned by all respondents for each parameter

B = Average Score assigned by all respondents for each parameter
Avg. Weighting = (7 + 5 + 9 + 3 + 6) / 5 = 6

C = Weighting based on avg. of 1 = Individual Weighting / avg. Weighting

D = Weighted Score = Score * Average Weighting = B * C
Satisfaction Index CSI = Average of (Weighted Scores)

CSI = (9.24 + 3.33 + 12 + 1.5 + 4.0) / 5 = 6.01

Since the scale used was 1 - 10, CSI = 60.10%

Thus Customer Satisfaction can be expressed as a single number that tells the supplier where he stands today and an Improvement plan can be chalked out to further improve his performance so as to get a loyal customer.