What separates a prejudice or an assumption from a scientific fact is the hard evidence. Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems.

Scientific evidence is information gathered from scientific research, which takes a lot of time (and patience!) to conduct. But there are a few things that all this research needs to have in common to make it possible for decision-makers, and ultimately all of us, to accept it as “evidence”.There are some criteria we want scientific evidence to fit into. First, it has to be objective and unbiased, which may be a hard thing to do keeping in mind that the majority of researchers constantly apply for funds.

According to Manu Saunders, a researcher and PhD candidate from Charles Sturt University, mostly, funds are distributed fairly. “But if an organization funds a research project that will benefit them financially, then we cannot accept the findings as 'evidence' unless different researchers (from unrelated organizations) come to the same conclusions through their own independent research.”

Moreover, since scientific evidence relies on data, it’s vital for researchers to ensure that the data they collect is representative of the “true” situation. Saunders argues that it means researchers have to use proven or appropriate ways of collecting and analyzing the data and ensuring the research is conducted ethically and safely.

Peer review and professional consensus is the most crucial step since it turns research into the “evidence” that we all talk about and rely on. “The researcher has to present their data, results and conclusions in the form of a scientific report or paper. This must be reviewed by their scientific peers – only they are qualified to assess the validity of the methods and the accuracy of the conclusions the researcher has drawn from the results,” Saunders explains.

It’s also very important to note that most scientific facts reach us though media and press, politics and opinion makers. Oftentimes, we don’t have the opportunity, time nor want to spend effort checking facts for ourselves.

Saunders argues that it’s a good idea to check if “scientific evidence” backs up its case by asking a couple of questions: “Who funded the research and why? How much evidence is there and how was it gathered? Was the sample size or location representative of the 'real' situation?”