2. 11/2010 5/2011 10/2011 5/2010 10/20125/2012 N N-1 N-2 N-3 5/2011 10/2011 5/2011 5/2010 10/2011 5/2011

3. Receive observation t Check observation (t- 1). Is it within 364 days of t? Check observation (t-2). Is it within 364 days of t? Keep observation t and (t-1). Yes No Yes No Keep observation n, (t-1), and (t-2). Delete observation (t- 1). Repeat process, replacing t with (potentially new) (t-1).

4. Receive observation t Check observation (t-1). Is it within 364 days of t? Check observation (t-2). Is it within 364 days of t? Keep observation t and (t-1). Yes No Yes No Keep observation t, (t-1), and (t-2). Delete observation (t-1). Repeat process, replacing t with (potentially new) (t-1).