Matrix sampling is a methodology to enhance the efficiency of measurement. In conventional measurement, every person in a group (e.g., every evaluation participant) completes every item on an instrument. In matrix sampling, each person completes only a sample of items, thereby reducing testing time for individuals. By averaging over persons who are measured, the performance of a group (e.g., evaluation participants) on a variable of interest can be estimated. Matrix sampling is used in situations where efficiency and economy are concerns, including large-scale summative evaluations and student assessment systems for nations, provinces, or states.