Justify a fieldwork sampling strategy

Question (8 marks): A student investigates whether pedestrian counts vary across three zones of Aberystwyth's CBD. Justify a sampling strategy and one method of data presentation, evaluating their limitations.

Mark scheme (levelled, 8 marks):

• Level 1 (1–3): Names a strategy (e.g. systematic) and a graph (e.g. bar chart) with limited justification.
• Level 2 (4–6): Justifies stratified sampling — three zones suggest the population is not homogenous, so stratifying by zone ensures representation. Justifies proportional symbol map overlaid on a base map of the CBD, allowing both magnitude and spatial pattern to be read. Identifies one limitation (e.g. time-of-day bias if all counts taken at lunchtime).
• Level 3 (7–8): Evaluates trade-offs explicitly — stratified sampling reduces sampling error but requires prior zonation which itself may be subjective; proportional symbols can overlap and obscure each other in dense zones. References reliability vs validity and suggests triangulation with secondary footfall data (e.g. council pedestrian counters) to test reliability.