It's a fine sunny day in the forest, and a rabbit is sitting outside his burrow, tippy-tapping on his typewriter.
Along comes a fox, out for a walk.
"What are you working on?"
"Hmmm. What's it about?"
"Oh, I'm writing about how rabbits eat foxes."
"That's ridiculous! Any fool knows that rabbits don't eat foxes."
"Sure they do, and I can prove it. Come with me."
They both disappear into the rabbit's burrow. After a few minutes, the rabbit returns, alone, to his typewriter and resumes typing.
Soon, a wolf comes along and stops to watch the hardworking rabbit.
"What's that you're writing?"
"I'm doing a thesis on how rabbits eat wolves."
"You don't expect to get such rubbish published, do you?"
"No problem. Do you want to see why?"
The rabbit and the wolf go into the burrow, and again the rabbit returns by himself, after a few minutes, and goes back to typing.
Scene: inside the rabbit's burrow.
In one corner, there is a pile of fox bones. In another corner, a pile of wolf bones. On the other side of the room, a huge lion is belching and picking his teeth.
It doesn't matter what you choose for a thesis subject.
It doesn't matter what you use for data.
What does matter is who you have for a thesis advisor.