Judging the reliability of a source typically involves a close internal examination of the sources used, tests performed, logic applied and information presented. At a bare minimum reliable sources should be as close to error free as possible. There should be transparency about the sources used and methods deployed to gather data. Conclusions should be laid out logically and follow from data presented.
The norms of reliability differ significantly depending on the type of business resource. Practical business information sources often omit precise citations in favor of brief attribution notes. Proprietary business reports won't expose the details of models used for forecasts or to calculate market share. Peer reviewed business scholarship should incorporate precise citations to related literature and data used, as well as describe methods in detail. Surveys, commonly used in business research conducted by both market researchers or social scientists should describe the sampling methods used. Sometimes such details are relegated to separate documentation or methodologies files.
This difference does not mean that you, as a consumer of business research, should be content with accepting unverifiable data. It means that if the information presented will be central to a business plan or study you are conducting, you may need to trace back to the original source. Fina original sources of information by searching library databases and googling. Some primary data sources may be behind pay walls.
Typical Attribution in Industry Profile
Source: S&P Capital IQ Industry Survey: Healthcare, Pharmaceuticals July 2014
Typical Attribution in Academic Publication
Blume-Kohout, M. E., & Sood, N. (2013). Market size and innovation: Effects of Medicare Part D on pharmaceutical research and development. Journal Of Public Economics, 97327-336. doi:10.1016/j.jpubeco.2012.10.003