I had submitted my application to the PhD program in Statistics, and in my statement of intent I specified that I would like to do a PhD research in Computational Biostatistics. I am in a Master's program right now and in this my last term I am taking a course in Statistical Learning. The problem here is that, I really like the materials covered in my Statistical Learning course, and now I want to do my PhD research in Statistical Learning / Data Mining, rather than doing Computational Biostatistics.
I already have exchanged few emails with a Biostatistics Professor at the university that I applied to, but no official contract was made between me and this Professor for me to do my PhD under this Professor's supervision. Also, the policy of this university is that new PhD students are initially not assigned a supervisor, but each new student will be choosing their supervisor towards the end of their first year, after taking the mandatory PhD reading course with a faculty member(s) that the student is interested in working with.
Is it okay for me to change the research area of interest that I specified in my statement of intent after submitting an application for a PhD program?