How to use statistics in college project work (Control & Experimental Group)

Hi,

I need some help to design my project work in a Rehab setting. I am trying to do a project work titled " Role of Traditional and Non-Traditional OT in Muscular Dystrophy". I am planning to divide patients into control and experimental group. Control group will receive conventional OT for 2 months & experimental will receive non-conventional OT too.
Based on the type of MD, OT interventions can be different within the experimental group also. I have read that if there are different types of patients in experimental group, one can use statistics to further narrow the findings. I need help if someone can brief me how to use concept of standard deviation etc within the experimental group itself. Please if possible explain me with a simple example of 30 patients (15 in each group). Out of 15 in experimental, each5 patients will have one criteria