The existence of stable conductance states in the ensemble of gramicidin channels incorporated into bilayer lipid membrane have been studied. Inconsistent estimators of density function are employed as a quantitative tool for description of systems with twolevel hierarchy of random processes having similar characteristic times. Non-parametric approach to investigation of histograms of membrane current fluctuations is developed. The expansion of histograms in terms of basic set of orthogonal functions and the use of the main components method allowed to visualize wanderings of image point throughout phase space аnd to evaluate the characteristic times of stable states which proved to be equal to 1-2, 5, and 9 seconds. Local membrane deformations caused by openings of separate channels are discussed as being responsible for interactions between gramicidin dimers. The advantages of application of non-parametric methods to investigation of cooperative effects in other biological systems are also considered.