##### Ha Nguyen-Thi

Lecturer
| Vietnam

# How to transfer distribution of probability parameter from 5 years into 1 year

Asked: 29 Feb 2020 |
458

Dear Dr and Prof,
I'm trying to find probability parameters for my model of chronic hepatitis B. However, most study I found come from observational studies, with different duration of follow-up . In my model, I need the probability and the parameters for beta distribution (alpha, beta). And I don't know how to transfer information in the literature to be used in my model.
I would like to pick up an example to illustrate. I want to estimate the annual probability of transiting from Immune tolerant (IT) state into immune clearance (IC) in Chronic Hepatitis B disease. I looked at literature and found some observational studies provide information about this, for example:
during a median follow-up of 8.2 years, 20 out of 102 patients transfered from IT to IC. So the probability during 8.2 years was 0.1961 and this probability followed the beta distribution, with alpha=20, beta=102-20=82.
Base on those information, I can calculate the annual probability of transiting form IT to IC is 0.0262. But how about the distribution parameters (alpha, beta) for 1 year?
I faced the similar situation a lot when I try to find the transition probabilities. So, I really hope that you could guide me what is the proper way to do this.
I'm looking for hearing from you and thank you so much for your help.