Figure out which rows DO NOT contain a value

I have a query that shows me a result set of documents that are attached to Orders within my system.  I need to be able to filter this result set and base the logic to see which ones DO NOT have a DocTypeID of 'WorkTick'

What I'm attempting to do is figure out which Orders do not have a work ticket associated basically this way I can create a report to show which orders don't have tickets but there are various document types so I'm a little confused on the best and most efficient means of doing so?  Its almost like I have to build the result set, and THEN loop through that result set to see which ones do or do not.  At least thats what I see at first glance.

Any help is VERY much appreciated and I will promptly respond and accept an answer

SELECT * FROM eDocData ORDER BY OrderNum DESC

The result set looks like so:

OrderNum      DocTypeID
87673                       NULL
87651                       DispTick
87625                       NULL
87622                       NULL
87550                       DispTick
87549                       WorkTick
87549                       DispTick
87546                      WorkTick
87546                      DispTick
87541                      NULL