Abstract--It is assumed that polluted environment reduces the quality of porcelain insulator in terms of leakage current. In this paper we conduct a correlation analysis to understand to what extent the influence of geothermal area to the quality of porcelain insulator. For that purpose, first, we test the equality of two correlation matrices by using Jennrich's test. Second, in case the two correlation matrices are not equal, we use principal component analysis (PCA) to study which variables are responsible to that situation. An example will be discussed and a recommendation will be addressed.Index Term -Correlation structure, Jennrich's test, principal component analysis, scree plot I.