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.
Systematic sampling is a statistical method involving the selection of elements from an ordered sampling frame. The most common form of systematic sampling is an equiprobability method. In this approach, progression through the list is treated circularly, with a return to the top once the end of the list is passed. k = N n {\displaystyle k={\frac {N}{n}}}.