PURPOSE OF SAMPLING:

When  the population is  too  large and spread oyer  a vast area, sampling needs to be  done for  the economy  of  time, energy and cost. But  it  is also necessary to  adopt a method  of  sampling by  which we  can generalize  about the population. This process of stretching the conclusions from the sample findings to  describe the total population is called  as generalization. 

Let us take the same example of rural mothers  of village A.  suppose we  study 100 rural mothers,  can we  then generalize and say from findings that these findings can be  extended  to  all the rural mothers of this village? We  can definitely generalize  the  findings on the 100 rural mothers  i.e.  the  study  sample, Whether we can generalize on all the mothers  of the village from which the sample was drawn would depend primarily  on how the  sample was drawn from the population. 

Researcher works with sample rather than with population because: 

-  It  is more economical in regard  to  time,'money,  material, efforts and resources, etc. 

- Accessibility of researcher  to  sample then  to entire population.

-  It  is practical and effective means  of data collection, because it is unnecessary  to gather information about some phenomenon from entire pqpulation. It  is  almost always possible to obtain a reasonably accurate understanding of problem understudy by securing information from a sample.