As readers, we seek out evaluative documents as much as any other type of writing. We search for reviews of new movies and restaurants; we surf the Web to learn about the strengths and weaknesses of products ranging from treadmills to smartphones to insect repellents; and we read editorials, letters to the editor, and columns in online magazines in the hope that they will help us develop an informed opinion about recent issues and events.

Writing to evaluate involves adopting the role of evaluator. Writers who adopt this role focus on reaching an informed, well-reasoned conclusion about a subject’s worth or effectiveness and clearly conveying their judgments to readers. Their writing is usually balanced, and they generally offer clear reasoning and ample evidence to support their judgments.

Writers typically evaluate a subject with one of three general goals: to determine whether something has succeeded or failed, to help readers understand how something might be improved or refined, or to help readers choose among alternatives. They form their conclusions by learning about their subject and considering how well it meets a given set of criteria — the standards or principles on which judgments are based.

Readers of evaluations typically share the writer’s interest in a subject and hope to learn more about it. They often share the writer’s assumptions about which criteria are appropriate — few readers, for example, expect movie reviewers to justify their choice of criteria. Readers expect the writer to provide evidence and reasoning to support his or her judgments, and readers usually want the writer to acknowledge and address alternative opinions about the subject. In fact, not only are readers likely to know that alternative opinions exist (usually through reading other evaluations) but they might also hold those opinions themselves. As a result, readers are likely to dismiss an evaluation that seems unfair or unaware of different points of view.

Writers’ decisions about criteria and evidence are shaped by the contexts in which they find themselves. Writers who address a general audience, for example, might need to define their criteria carefully, while those who write to professionals in a particular field might reasonably expect their readers to be familiar with the criteria they’ve selected. Similarly, a writer’s choice of evidence reflects the nature of the subject and readers’ knowledge, expertise, and social and cultural backgrounds. For instance, an evaluation of a creative production such as a movie or a television documentary will usually draw most heavily on the subject itself for evidence, citing examples from the work and referring to expectations about the genre to support the writer’s judgments. An evaluation of a building restoration project, on the other hand, is likely to bring in evidence from outside sources — such as budget reports, building codes, and interviews with community members and architects — to support the writer’s assessment of the project’s relative success or failure and recommendations for improving it.

Evaluative documents make important contributions not only to our personal lives but also to written conversations. On an individual level, evaluations help us make decisions that can affect everything from the brand of car we drive to how we vote in the next election to where we attend college. Within a written conversation, evaluations provide the basis for making collective judgments about how to move the conversation forward.