How to find corroborating evidence

Corroboration is the ability to compare information provided by two separate sources and find similarities between them.

When a second source provides the same or similar information to the first, the second source is considered to corroborate (e.g. support, or agree with) with the first.

Finding corroboration between sources strengthens your conclusions, especially when you are making a historical argument.

When choosing sources to corroborate, pick those that are deemed particularly reliable, which adds further certainty to your claims.

Watch a video explanation on the History Skills YouTube channel:

In order to identify information that is agreed upon by two different sources, following these steps:

1. Read the first source and summarise the key points of historical information it provides. Using direct and indirect quotes helps with this.
2. Read the second source and summarise the key points of historical information it provides. Using direct and indirect quotes helps with this.
3. Compare the two different summaries that you wrote and then look for the same or similar information in both lists.
4. Any information that is similar between the two can be used as evidence for corroboration.
5. Any information provided by one source that is not found in the other cannot be used in corroboration. 

To help you complete the above steps successfully, you can use a Venn Diagram or a table like the one below, to organise your thoughts:

If, in the process of finding corroboration between sources, you find that the two sources provide information that is different to each other, you have potentially discovered contradiction between them. This is another source analysis skill and you can find out more about contradiction here.

Demonstrating source corroboration in your writing:

Both Smith and Jones agree on the fact that Spartan battlefield expertise was the key to their ongoing success as a Greek power. This is clear when Smith says that “the Spartans’ victory was dependent upon their superior military training” (1981, 31), which is supported by Jones who says that “the Persians could not match the Spartan’s disciplined tactics” (1994, 56-62).

Caesar’s subsequent use of Gaul’s wealth to fund his political exploits is outlined by Dillon and Garland, who state that through “conquering, pillaging and massacring in Gaul, ... [Caesar]...gained enormous amounts of wealth with which to pursue his political aims at Rome" (Dillon and Garland, 2005, 546). The importance of securing a wealthy province to advancing Caesar’s political career is further corroborated by Frederiksen, who states that "Caesar's…early career was sped by means of huge debts, and it was not until the gold of Gaul became available to him that the tables could be turned” (Frederiksen, 1966, 130).