I am trying to fit my data with a bimodal distribution using two beta distributions, however it seems to me that the two peaks are not captured very well. The reason that I notice from the data is that it has too many zeros and 100s. I had tried to use mixtool, gamlss and flexmix in R but none of them provided me a satisfactory fitting. Mostly, they have problem with convergence. Thus, I wrote my own EM algorithm to fit it and fortunately it can be fitted using two betas or two normals (please see attached). I have the following questions:
- With this type of distribution (bimodal and high point mass around each peaks), what is the best mixture model to fit and respective algorithm, EM, etc.?
- Rather than mixtool, gamlss and flexmix pakages, is there any other that can be used to fit the bimodal distribution?
I am looking forward to hearing your advice and experience.