Since STAT 501, 502, and 503 courses are only 5 weeks long, they have different add/drop dates.  I have listed them here just for your information.  (I realize they do not correspond well with the actual dates of the courses, but these add/drop dates are set by the Registrar's Office and are not under my control to change.) 
 
STAT 501 Course Dates:(1/20-2/22) Last Day to Add: 1/20 Last Day to Drop: 2/3 
STAT 502 Course Dates:(2/23-4/5)  Last Day to Add: 2/17 Last Day to Drop: 2/24 
STAT 503 Course Dates:(4/6-5/10)  Last Day to Add: 3/24 Last Day to Drop: 3/31 
 
 Also, based on current plans, Spring 2015 is the last semester that these courses will be offered on a regular basis.

Finally, the work-load for the three course sequence STAT501-503 is the same as a 3-credit semester-long course.  Even if you take just one of the courses, for the corresponding 5-weeks, it will be as if you are taking another 3-credit course.  So, please plan your schedule accordingly.
 
Dr. Davis