Which type of data is characterized by its lack of formal documentation?

The choice of informal data is correct because informal data typically lacks the structured and standardized documentation that characterizes formal data sources. Informal data is often collected through observations, casual conversations, or unstructured feedback, and it can provide valuable insights into situations or behaviors that are not captured through formal assessments or surveys.

In contrast, formal data is systematically gathered using structured methods such as standardized tests or official reports, ensuring consistency and reliability. Summative data refers specifically to assessments that evaluate student learning at the end of an instructional unit, often requiring formal documentation to measure effectiveness. Criterion data is used to measure performance against specific standards or criteria, which also necessitates formal documentation to ensure accurate assessment.

Thus, informal data stands out due to its fluid nature and lack of formal processes, making it distinct from the other types of data mentioned in the context.