Source Analysis 101



30 January 2014

When analyzing sources, the first question we ask ourselves should be: “Is this an original or a derivative?”  However, this basic question is just a starting point for our evaluation of reliability. Some material falls clearly into one extreme or the other, but many resources fall somewhere on a sliding scale between those extremes.

Under the law  “originals” can be facsimiles—image copies made by photography or digitization. They might be duplicate originals, as with many early census records. They might be record copies of the ilk we find in courthouse ledgers.

Narrative accounts complicate this mix. Good historical works are ones in which authors have distilled evidence from many different sources, defined correlations and dichotomies, and reached conclusions. Those works are a derivative in the sense that the information has been processed and presented in a different form. However, each narrative is an original work in the sense that it uniquely assembles a chosen body of evidence and presents the author’s analyses and conclusions in the author's own words.

All things considered, the degree of credibility carried by any “original,” “derivative,” or “narrative account” is something we cannot determine just from a label. Our decision about credibility has to be based on a critical analysis of many aspects of each source, the information it offers, and the evidence we draw from that information.


  • EE’s bibliography defines all the italicized terms.
  • EE 1.24-1.27, 1.30-1.41 treat these basics in greater detail.
  • EE3.12, 11.51, 12.75, 12.72, 12.79, and 13.33 add other perspectives that focus on specific record types.
  • QuickLesson 17: “The Evidence Analysis Process Map” ( provides a fuller discussion of the relationship between sources, information, and evidence.