A sample which is typical in respect of certain specified characteristics of the population or material from which the sample is collected. For example, in statistical sampling, selecting only large units from a mixed population of large and small units would give a sample that is typical of the large units; however, it would be a non-representative sample of the mixed population. To obtain a representative sample of this mixed population, the population should first be divided into two separate groups of large and small items and these groups sampled separately. In material sampling, homogenization of material (e.g. solutions) prior to sampling may be required to obtain a representative sample.