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.
Types of non-probability sampling methods : Convenience - aka chunk, accidental & incidental sampling: Selection of the most readily available people or objects for a study: No way to determine representativeness : Saves time and money : Quota: Selection of sample to reflect certain characteristics of the population