Sampling at random method

- Set up a grid – (10m X 10m would be reasonable) - Generate random co-ordinates using a random number table (to prevent bias) - Place the bottom left hand corner of a 1m X 1m quadrat at the generated coordinates - Measure the limpet closest to the centre (to eliminate bias) - Repeat for 30 limpets (30 is good for statistical analysis !) this allows you to calculate a reliable mean. - To make data valid – same species of limpet, same height from sea level, same time of year