A pamphlet written by a group opposing unions : This account is likely to be biased because it is written by people who want to argue against unions.
A journal written by an employee at a factory: This account would be written by someone who knows the situation well, but also has no secondary motive for recording it.
A novel written to encourage factory regulation : This novel would be biased, just like the first example, because it would try to provide reasons for an ideological position through its narrative.
A collection of letters written by a farmer: A farmer would be less acquainted with the conditions of factories than a factory worker.
