Documentary materials (letters, speeches, etc.) and literature are also potential data sources. In reviewing text materials, it is important to identify whether the text is extant (those the researcher did not shape, such as letters or diaries) or elicited (those in which the researcher involved participants in writing, such as through an Internet survey). Text used in the study must be situated in the context. The researcher must consider who produced it, how it was produced, its purpose, its structure, its language, embedded meanings, and more. Data are analyzed by searching for similarities and differences among the participants' responses about the experience.