Ghost is you after you die. So you die, then you become a ghost. See my following old post which explains that ghost is simply the next milestones that you move to after your death.
Ghost is the next Milestone After Your Death
So, is ghost real? Of course, it is real because it is always there. After you die, you just move on and you don't stop there because that is how the entire universe or system works. Although it is always there, it doesn't mean you can communicate to them. Some who are able to communicate or believe the ghost is there, then ghost is real to them and vice-verse.
The reason why we can't communicate to them is their energies after death are scattered around, they are not concentrated. In other words, they don't move to just one milestones but multiple milestones. This is something new as I haven't explained this multiple milestones concept before. :) In reality, it is always multiple milestones, the single milestone is used to explain thing in a easier way.
If you look at a microscopic world, we all made up by energy (quantum physics). Imagine 100% of energy that makes up who you are and when you die, what will happen to these energies? They just spread out to different forms of energy. For instant, if it spreads to 10 X 10%, then you're hard to be detected after your death. On the other hand, if it spreads to 90% + 10%, the 90% which makes you can be easily detectable as compared to 10 X 10% spread. That's why you see those haunted places are usually due to those unpeaceful death because their energies are concentrated after death.
So now back to the question, is ghost real? I'm making assuming real is something that we can feel or communicate to. Then, I think:
Ghost Is Real If It's Energy Is Not Scattered Around
Hope it does make sense! Do comment if you believe in ghost or not. :)