Such data include narratives of events written by participant observers, accounts of what the participants understood about an event, reports of what was said at a meeting or an interview, observational records of how an event took place, and statements of impressions about what was going on, why it was happening, and how people felt about it, their own self, or each other.
The data was made up of objective facts so it would not be influenced by mass opinion subject to influence by ulterior motive and gossip of other people as that would be unfair to the target of study in the case.