Question

What is random sampling and how is it used in the ecology population?
What limits the accuracy of this method?

Answer 1

The aim of sampling is to select a sample which is representative of the population .

One such type of sampling done in ecology is random sampling. In random sampling any number of population has an equal chance of being selected. Random sampling is used to select a sample that is unbiased.Random sampling is usually carried out when the area under study is fairly uniform, very large, and or there is limited time available. When using random sampling techniques, large numbers of samples/records are taken from different positions within the habitat. A quadrat frame is most often used for this type of sampling. The frame is placed on the ground (or on whatever is being investigated) and the animals, and/ or plants inside it counted, measured, or collected, depending on what the survey is for. This is done many times at different points within the habitat to give a large number of different samples.

In the simplest form of random sampling, the quadrat is thrown to fall at ‘random’ within the site.

However, random sampling has its own limits.For example, randomly located quadrats are often difficult to accurately locate, particularly when an extensive area is sampled, and a large proportion of sampling time is devoted to locating the quadrats. In addition, a larger sample size is needed to obtain adequate precision under random sampling, because the technique ensures that all the variability of the population is represented in the sample. Therefore, simple random sampling designs usually feature low sampling efficiency. Finally, random selection processes may lead to an uneven distribution of sample units across the site, so that some areas may be poorly represented during sampling.