The diagram (right) shows the basic parts of the modern plough: 1  beam. 2  hitch (Brit: hake) 3  vertical regulator. 4  coulter (knife coulter pictured, but disk coulter common) 5  chisel (foreshare) 6  share (mainshare) 7  mouldboard.
Non-probability sampling is a type of sampling technique whereby all the units of a population do not have an equal chance of being selected in the sample.
Non-probability population sampling method is useful for pilot studies, case studies, qualitative research, and for hypothesis development. This sampling method is usually employed in studies that are not interested in the parameters of the entire population.