In random sampling every individual or position in the area has an equal chance of being chosen. This removes sampling bias.A common method for sampling plants or slow-moving animals uses quadrats:1. Lay out two tape measures at right angles along two edges of the area to make a grid.2. Use a random number generator (or random number tables) to produce a pair of coordinates.3. Place the quadrat at these coordinates and record the organisms present, for example the number of individuals or the percentage cover.4. Repeat for a large number of quadrats and calculate a mean.
Random sampling is suitable when the area is fairly uniform. If there is an obvious change across the area, such as from a shaded to an open region, a random sample may miss the pattern.Random sampling can also be used for other investigations, for example choosing leaves or individuals from a population by giving each one a number and using random numbers to choose which to measure.
Random sampling is suitable when the area is fairly uniform. If there is an obvious change across the area, such as from a shaded to an open region, a random sample may miss the pattern.Random sampling can also be used for other investigations, for example choosing leaves or individuals from a population by giving each one a number and using random numbers to choose which to measure.