Vendor rating is a process having strategic implications for managing a sup
ply chain. Vendor rating can be done using analytic hierarchy process eithe
r by a single decision maker or by a group of decision makers. This approac
h may suffer from some drawbacks including bias in estimation process. A me
thodology is proposed in this paper which makes use of estimation of the ra
ting by a group on an individual basis following the principle of anonymity
. A statistical analysis is carried out to determine the confidence interva
ls for the estimates of the composite rating of the vendors. The procedure
presented here helps in identifying those members whose opinions may signif
icantly deviate from that of the group. Emphasis is placed on establishment
of confidence limits in group decision-making. Participants in group decis
ion making, whose opinions fall outside the group's confidence limit, are f
urther studied to understand the source of variation. Implementation guidel
ines have also been provided to account for the dynamic nature of the vendo
r evaluation process and to take appropriate actions in managing the vendor
rating process in the overall supply chain.