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.
This sampling is carried out when the parameters of the entire population are not required. This type of sampling is easy, cheap and quick but not accurate. Non-probability sampling can be classified into 5 types. Convenience sampling: In this sampling subjects are selected on the convenience of the researcher.