Likelihood functions and some maximum likelihood estimators for symbolic data

Likelihood functions are the foundation of many statistical methodologies in classical data analysis. Likelihood functions for symbolic data must be introduced before these classical methods can be extended to the analysis of symbolic data. In this paper, we propose the likelihood function for symbolic data and illustrate its applications by finding the maximum likelihood estimators for the mean and the variance of three common types of symbolic-valued random variables: interval-valued, histogram-valued and triangular-distribution-valued variables.