Research on ?organizational purchase behavior? is less developed compared to research on
?consumer purchase behavior? due to the difficulty to get data from industries and organizational purchase
behavior is influenced by more factors than consumer purchase behavior. Because of these reasons not
many people willing to take a research on organizational purchase behavior. Some researchers who have
studied organizational purchase behavior, most of them only emphasize on: purchase process, department
influence, organizational size and organizational structure. Only few of them who studied interpersonal
process especially in the area of ?power? owned by individual members of buying center in the company.
Latent power is the important key that can control and influence to other member team of buying center to
agree with his or her decision. This research is using 188 respondents of buying center from 30 Indonesian
coal buying companies, such as: Power Plant, Cement Plant, Paper Plant and Trader company. This
research are use clustering and regression technique. Clustering technique is used to grouped the research
objects and identify the characteristics of each object. Regression method is used to identify which power is
the most dominant to influence the purchase decision on buying center. The result on this study are:
Indonesian coal purchaser based on the buying center characteristics, situational characteristics and
individual behavior: can be divided to be five cluster, such as: (1) high familiarity & viscidity, (2) high
consideration to government regulation, (3) high risk, (4) small member size and high influence attempt and
(5) high time pressure. Using the regression technique on each cluster, can be identified the strongest power
that influence to the buying center, there are: cluster 1: ability on management power, cluster 2:
reinforcement power, cluster 3: ability on engineering power, cluster 4: reinforcement power and cluster 5:
reinforcement power.