5.3: Characteristics of Good Supporting Evidence

There are two kinds of truth. There are real truths and there are made-up truths.
-Marion Barry
(As Mayor of Washington, D.C., after his arrest for drug use.)

Though different professions and academic fields have their own standards of what is "good" evidence, there are some common characteristics to consider.

Trust

Is the information from an authoritative, trustworthy source? Will your audience trust this source and should you? In the previous chapter we stressed the importance of being cautious with Internet sites, but you should be wary of any source’s credibility. Also, remember that it’s better to refer back to original material than rely on someone else’s interpretation of existing work since people and their research are often misquoted.

Accuracy

Is the information accurate and free from error? Check and recheck your facts-errors can seriously damage your credibility. Critically evaluate your sources and if you’re uncertain about your facts, be honest with your audience. You can increase your confidence in the accuracy of your information by using multiple sources to confirm key facts.

Precision

Is your information appropriately precise? When we talk about "precision," we mean the information should be specified within appropriately narrow limits. The level of required precision will vary with the topic being discussed. Describing regulations for uniform wear may require a precision of fractions of an inch and telling someone that his operational specialty badge should be in the middle of their shirt or within a meter of his belt buckle is not adequately precise. On the other hand, when reporting on the designated mean point of impact for munitions, a measurement in meters or feet would be an appropriate level of precision.

When talking about some subset of a group, explain how many or what percentage of the total you’re talking about. If you find yourself constantly using qualifiers like "some, most, many, almost, usually, frequently, rarely..." you probably need to find some convincing statistics to help you make your case.

Relevance

Is your evidence relevant? Evidence can be authoritative, accurate and precise, yet still be totally irrelevant. Don’t shove in interesting facts that have nothing to do with the claim; help the reader understand the relevance of your material by explaining its significance. Explain charts, graphs and figures and use transitions in your writing to "connect the dots" for the reader.

Sufficiency

Is your evidence sufficient to support your claim and representative of the whole situation or group? If you are trying to form some conclusions about a situation or group, you need data that represents the complete situation. For example, if you were trying to form conclusions about the overall military population, you would want to gather evidence from all services, not just one career field in one service. If you find that your evidence is either not representative or not sufficient, you need to find more evidence, limit the claim to what you can prove or qualify your claim. You may have to let go of evidence that doesn’t fit or data that is no longer current.