Random Sampling

Each element within the subject matter (within statistics this is called a population) has an equal chance of being selected. The selection of any individual is totally independent of any other selected, or non-selected, individual.

The use of random numbers tables can assist in selecting which individual is to be included in a survey. Excel has the ability to produce random number tables.

If, for example, you had an area of 10,000m² (one hectare) with low growing vegetation and wanted to use the quadrat sampling technique. On the assumption you weren't going to use a 1m x 1m quadrat and cover the whole area, you would sample a number of individual areas (each of 1 x 1 m).

You may wish to sample say 50 x 1m² plots. A random number generator for between 1 and 10,000 can be put into Excel spreadsheet, covering 50 cells, to create 50 random numbers. If an imaginary grid is placed over the area to be surveyed then the locations for the samples can be readily determined.