Reliability of sources evaluates whether they are trustworthy. It is important that the sources you use in your assessment pieces are reliable so that the quotes you use from them can be trusted.

In history, it is rare that we are completely sure that sources are 100% reliable. Therefore, when we talk about reliability of sources, we can talk in terms of ‘degrees of reliability':

Extremely - Very – Somewhat – Rarely – Not very

For example, we can say that a source is "extremely reliable", or "not very reliable".

A judgement of reliability requires three elements:

1. A clearly stated decision
2. A 'marker' word to show the link between the decision and the reasons (e.g. because, due to, since, etc.)
3. Reasons for the decision (from your source analysis)

Examples:

This source is very reliable because it was written by a professional historian.

As the author was present at the event, his record of it is likely to be very trustworthy.

Based upon what you discovered in your analysis of the source, the reasons provided to establish reliability can be based upon any of the following:

Source A is a very reliable source regarding the experience of Australian troops at Gallipoli because it is a letter was written by John Smith, an Australian soldier who was personally involved in the event itself. This source was written a few days after the Gallipoli landing on the 25th of April 1915 and was intended to be a recount of his experiences to be read by his family in Australia. As a result, it is likely to be a very trustworthy account of a soldier’s experience of the Gallipoli landing.

When using information from sources to prove your own argument, you need to be able to use sources that are reliable. If you have found a source which you discover to be unreliable, the best advice would be not to use the source.

However, if the source is too relevant to your topic that you cannot use another, use a different evaluation skill to argue for why you are using it, rather than simply arguing that the source is unreliable.

Based upon what you discovered in your analysis of the source, you can establish its unreliability based upon any of the following:

• The creator of the source was not present at the time of the event.

• The creator of the source does not have a sufficiently educated perspective on the topic. (e.g. they have no formal education in History)

• The source has not been fact-checked by an educated audience. (e.g. it is a online blog post)

• The purpose of the source was to be entertaining or to simply give an opinion, rather than focus on the facts, about the topic. 

Demonstrating source reliability in your writing:

This source is mostly reliable regarding factory conditions in the Industrial Revolution because the creator lived next to a major industrial facility during the 19^th century.

John Smith, whose own personal experience as a soldier in World War I provides a highly reliable description on the living conditions in the trenches, says “…” (1981, 31).

This official population survey was conducted by the Australian Bureau of Statistics which is responsible for providing the Australian government with official data. As a result, the information provided can be considered very reliable.

Demonstrating source unreliability in your writing:

Plutarch describes what happened, saying, “…”, but he often wrote to entertain so historians can’t always trust what he says (as found in Scott-Kilvert 1960, 76).

The information is drawn from a random website that does not provide information about the author, so it is probably a very unreliable source.