Let’s say you’re conducting a scientific survey on the percentage of cancer patients who were chain smokers in the past.
But how can you prove that all volunteers in the survey were actually cancer patients?
Leaking their diagnostic reports? That wouldn't be good for their privacy.

Solution? Zero-Knowledge Proofs!

We know that cancer is a genetic disease caused by changes in genes that control how cells grow and multiply. Cells are the building blocks of your body, and each cell contains a copy of your genes, which function like an instruction manual.
Source of Information : https://www.cancer.gov/about-cancer/causes-prevention/genetics#what-kinds-of-genetic-changes-cause-cancer

So, instead of revealing sensitive medical records, we can generate a proof that all our volunteers possess a specific genetic marker found in cancer patients, without disclosing their actual identities or medical history.

This was just an example, you can use such technique in any scientific survey or research!