A college has 84 students in the North campus, 96 in the Central campus and 120 in the South campus. A researcher proposes a sample containing 14 randomly selected students from the North campus, 16 from the Central campus and 20 from the South campus.
State the sampling technique proposed.
Show that the allocation is proportional to campus size.
Give one advantage of the proposal over selecting 50 students by opportunity sampling at the Central campus.