Which of the following is NOT a characteristic of observational methods?

Observational methods are typically focused on gathering data through direct observation rather than through modeling or simulation techniques. The primary characteristic of these methods is that they rely on what can be seen and recorded in real-time or through existing records, making them particularly useful for analyzing what has occurred in a project.

The reason that "allow for insertion of fragnets" is not a characteristic of observational methods is that fragnets, which are fragments of a project network that can be inserted into a schedule, usually pertain to modeling and scheduling techniques like Critical Path Method (CPM) or program evaluation review technique (PERT). Observational methods do not involve creating or modifying project schedules; they rather document and analyze completed or in-progress activities.

The other characteristics listed highlight the nature of observational methods: they are indeed useful for retrospective analysis as they allow for studying past project data; they usually do not require detailed project modeling since observations are based on actual performance rather than theoretical constructs; and the effectiveness of observational methods is significantly influenced by the quality of available records, as good records provide more accurate insights into past project performance.