TARGETS FOR REVISING
Rationale
Easy to Spot
Harder to Spot
Simple Sentence Syndrome

The referent of anaphora is not always obvious.

Example:

   The investigators discovered that the researchers had falsified their results.  This means that they would have to submit . . .

Notice that in the above example, the idea that this refers to is still not clear for seven words after it is used;
this could refer to the fact that the researchers falsified their results, or this could refer to the fact that the investigators discovered the falsified results.