Sampling

Sampling is usually necessary because time, equipment and access are limited. The aim is to collect enough relevant evidence to represent the places or people being studied without making the investigation unmanageable.

Sampling means choosing a manageable set of sites rather than measuring everywhere. Sites at regular intervals can help investigate downstream change, but restricted access may limit the choices. A question must remain realistic for the sites that can be investigated safely.

For the pebble-size and gradient enquiry, students could select sites at regular intervals along an accessible stretch of beach. This is systematic sampling: it spreads observations along the study area rather than concentrating on the easiest or most striking sites. At each site, they could measure pebble sizes using a consistent sampling method and record the beach gradient using the same procedure.

Sampling makes an enquiry manageable, but the sample must still represent the area or population relevant to the question.