Which quantitative investigation technique is a form of observation?

Activity sampling is a quantitative form of observation used to collect measurable evidence about how work is performed. Instead of continuously observing one person or process, the analyst samples activities at intervals and records what is happening. This helps identify how time is spent, how often particular tasks occur, and where inefficiencies may exist. Surveys are quantitative but they gather responses from participants rather than observing actual work. Interviews are primarily qualitative because they rely on discussion and stakeholder explanation. User role analysis is used to understand user types, responsibilities, and interactions, but it is not a form of observation. Since activity sampling directly observes work and produces measurable data, it is the correct answer.