Independent sources

The term "multiple independent sources" in journalism, criminal justice, science and general research, are two or more unconnected people, organizations, or objects which provide a given set of information or samples. For example, two separate people who see a traffic accident, at the spot, could be considered independent sources. However, if one person saw the accident and told the other one about it, then they would not be "independent", since one would "depend" on the other for their information. Also, if two witnesses to an event discuss what they saw before they are asked about it and agree to tell the same story, then they are also no longer independent. As another example, two scientific devices could be considered independent sources of measurement data, unless they shared the same wiring or electrical power supply (or similar factors).
Consulting multiple independent sources is a common technique for detecting errors and deception, as any divergences or contradictions between statements, or data samples, would likely indicate one of these.
Famously, the "New York Times' " minimal standard for reporting a fact not otherwise attributed to a single speaker is that it be verified by at least two independent sources.
Circular reporting is a situation where multiple sources "appear" to be independent, but in reality originate from a single source. Because circular reporting can happen inadvertently in many situations, extra care must be taken to ensure that multiple sources actually are independent, rather than interconnected in an obscure manner.