I think I came up with an example. data test; set sashelp.class; do i=1 to 5; N=_n_; output; end; run; I created this dow-loop example by putting set inside do group which does not quite make sense. data test; do i=1 to 5; set sashelp.class; output end; run; ... View more

Thanks, Reeza and ballardw.  Is there any exmple of  explicit loop and implicit loop working  together?  I have heard about dow-loop, I wonder if it is example of interplay of inner and outer loop. ... View more

Thanks, ballardw.  The code posted above gives me desired result (it deletes from both data sets).  I don't want to create temporary variale now (just for learning purpose) . I wanted to know how the data step worked.  Since set statment in my example stacks a and b together sequentially, does "if " statement operate on each data sets sequentially.  Basically, I want to see what happned during _n_=1?  ... View more

Thanks for clarification. ... View more

Haikuo, may be I am missing something important. When data step reads Sue, isn't _n_ becomes 2. What is logic behind "do group" starting form _n_=1? I am assuming when _n_=2 it is asking to iterate to 2 (Num_chances). So there is interplay of two kinds of _n_? when I put index "i" instead of _n_, it gives same result. ... View more

Thanks, FreelanceReinhard. ... View more

Thanks, PG. This helps a lot. ... View more

Thanks Quentin. ... View more

FreelanceReinhard, I checked the difference between compile phase and execution phase before posting this question. I know  intializing to missing values was the part of the execution phase. Since the set statment never executes, I thought it does not  initialize ; just compile the variable names only. So my take was even without stop statment it should contain only variable names  not missing observartions.  http://www2.sas.com/proceedings/sugi23/Begtutor/p50.pdf ... View more

Thanks, ballardw. ... View more

I think this was what I want to see as the effect of return statment. ... View more

Thanks, Haikuo.  ... View more