What do you mean by sample, population and the variable of interest of a data set? Sample, population and the variable of interest of a data set

 

a.      What do you mean by sample, population and the variable of interest of a data set?

 

Population: 

 

  It is the target data in which we would like to know about various aspects. Ex: age, height of people of US (Population).

Sample: It is a subset of the Population data set, a part of the population forms a Sample.

Variable of interest: The property/aspect which is to be compared or presented of a particular Sample/ Population.

 

Pollsters regularly conduct opinion polls to determine the popularity rating of the current Prime Minister. Suppose a poll is to be conducted tomorrow in KPK, in which 2000 individuals will be asked whether the PM is doing a good or bad job. The 2000 individuals selected by random-digit telephone dialing and asked the question over the phone:

 

i.                    What is the relevant population in this situation?

Answer: 2000 is the Target Population.

ii.                  What is the variable of interest? Is it quantitative or qualitative?

Answer: The variable is "Performance of PM”, it’s Qualitative since we are taking the opinion (good/Bad).

 

iii.                How to make decision based on the sample of 2000 individuals?

Answer:The Percentage opinions of "Good" & percentage "Bad" of 2000 responses are compared.