There are several interesting elements to Macbeth that could be the basis for a research paper. What I have always been most fascinated by is the historical elements of the story. After all, there were some real people on which events and characters are based. Determining how much fact and how much fiction is there would be fascinating.
There is a historical basis to the play.
Shakespeare drew from many sources when he wrote—the Holingshed Chronicles of England was one of these. (enotes, historical context)
A good place to start would be with this statement of Malcolm’s that has always interested me.
My thanes and kinsmen,
Henceforth be Earls, the first that ever Scotland
In such an honor named. (Act 5, Scene 8)
This line has always interested me, but I never really took the time to determine how historically accurate it is. Did Scotland have thanes? Do they now have earls? When was this change made? What prompted it? Fascinating stuff!
Other historical accuracies might be researched, including the popularity and/or use of witchcraft in Scotland during Macbeth’s time.
The question is, how does this historical information influence our reading and understanding of the play? Does it matter? Did Shakespeare intend for us to care? Why did he make the changes he made? All are fascinating research topics.