Purposive or Judgement Sampling

Under this method of sampling, the choice  of selection of sample  items from the universe  depends exclusively on the judgement  of the investigator. For example, if 10 students form a class  of 60 students  are to be selected for the survey of  spending habits of students the 10 items  may be selected by the investigator  himself which he considers to  be representative of the whole class.

Merits:

(1)   Where small number of units is in the inverse, random selection may miss the vital elements, but this method of sampling would surely include them in a simple.

(2)   Where an investigator wishes to study some unknown traits of the universe and some of which are know. Thus  he will  stratify  the universe  according  to known elements to select  sample units form  each  stratum on the    basis  of judgement  as such   this method is used obtain  more  representative sample.

(3)   This method saves time and money both   as public officials are often pressed for time.

Limitations:

This method is unscientific since the units selected from the universe may be affected by personal bias.

The success of this method depends upon excellence in judgement, if the investigator has no good judgement, sample will not be representative. The conclusions based on sample will be wrong and erroneous.