Evidence provides evaluators with a basis for making their judgments. Evaluative essays tend to rely on a mix of evidence from published sources, observations, and personal experience.

Some evidence is quantitative — that is, it can be measured. For instance, the rate of inflation over the past decade or the number of people participating in a noontime activity program can be found through sources such as public documents or direct observation. Other evidence is qualitative — that is, it is based on the writer’s experiences with and reactions to the subject. Music reviewers, for example, usually base their evaluations on the originality of the music, the quality of the performance, and the quality of the recording and production. Some criteria, such as cost, can be judged on both quantitative and qualitative evidence. For instance, you can calculate the amount of money that would be required to pay for a particular program or solution, but you can also view cost in terms of its impact on quality of life or on the environment.

To identify evidence for your evaluation, list the criteria you’ll use to conduct your evaluation. Determine whether each criterion will rely on quantitative or qualitative evidence. Then pinpoint potential sources of evidence for your evaluation by reviewing your initial research and any notes you’ve taken. Next to each criterion, list the evidence on which you’ll base your judgments. If you find that you don’t have enough evidence to support a thorough evaluation, look for more information.