COLLECTION OF DATA
Points to remember:
1. Collection of data is the first important aspect of statistical survey.
2. Data – Information which can be expressed in numbers.
3. Two sources of data – Primary & Secondary Primary data – data collected by investigator himself secondary data – data collected by someone and used by the investigator.
4. Difference between Primary and Secondary Data
a] Primary data is original data collected by the investigator while secondary data is already existing and not original.
b] Primary data is always collected for a specific purpose while secondary data has already been collected for some other purpose.
c] Primary is costlier or is more expensive whereas secondary data is less expensive.
5. Methods / Sources of Collection of Primary Data :
a] Direct Personal Interview – Data is personally collected by the interviewer.
b] Indirect Oral Investigation – Data is collected from third parties who have information about subject of enquiry.
c] Information from correspondents – Data is collected from agents appointed in the area of investigation.
d] Mailed questionnaire – Data is collected through questionnaire [list of questions] mailed to the informant.
e] Questionnaire filled by enumerators – Data is collected by trained enumerators who fill questionnaires.
f] Telephonic interviews – Data is collected through an interview over the telephone with the interviewer.
Questionnaire – A list of questions with space for answers.
6. Pilot Survey – Try-out of the questionnaire on a small group to find its short comings.
7. Qualities of a good questionnaire :
a] A covering letter with objectives and scope of survey.
b] Minimum number of questions.
c] Avoid personal questions.
d] Questions should be clear and simple.
e] Questions should be logically arranged.
8. Difference between census method and sampling method.
Census Method | Sampling Method |
Census Method | Few units of population are studied |
2) Reliable and accurate results | Less Reliable and accurate results |
3) Expensive method | Less expensive method |
4) Suitable when population is of homogenous nature | Suitable when population is of heterogeneous nature |
Personal Interview Method : | |
Advantages | Disadvantages |
1) Highest response rate | Most expensive |
2) Allows all types of questions | Informants can be influenced |
3) Allows clearing doubts regarding questions | Takes more time |
Mailed Questionnaire Method: | |
Advantages | Disadvantages |
1) Least expensive | Long response time |
2) Only method to reach remote areas | Cannot be used by illiterates. |
3) Informants can be influenced | Doubts cannot be cleared regarding questions |
Telephonic Interview Method: | |
Advantages | Disadvantages |
1) Relatively low cost | Limited use |
2) Relatively high response rate | Reactions cannot be watched |
3) Less influence on informants | Respondents can be influenced |
1.Census Method – Data collected from each and every unit of population.
2.Sample Method – Data is collected from few units of the population and result is applied
to the whole group.
3.Universe or population in statistics – Total items under study.
4.Sample is a section of population from which information is to be obtained.
Sources of Secondary Data:
1. Published Source – Government publications, Semi-government publications etc.
2. Unpublished Source – Census of India [They are collected by the organizations for their own record]
Sampling Methods: 1] Random sampling 2] Non-random sampling
1. Random Sampling – It is a sampling method in which all the items have equal chance of being selected and the individuals who are selected are just like the ones who are not selected.
2. Non-random sampling – It is a sampling method in which all the items do not have an equal chance of being selected and judgment of the investigator plays an important role.
Types of Statistical errors:
1] Sampling errors 2] Non-sampling errors
Sampling Error: It is the difference between sample value and actual value of a characteristic of a population.
Non-sampling errors: Errors that accurate the stage of collecting data.
Types of non-sampling errors:
a] Errors of measurement due to incorrect response.
b] Errors of non-response of some units of the sample selected.
c] Sampling bias occurs when sample does not include some members of the target population.
Census of India – It provides complete and continuous demographic record of population.
National Sample Survey Organization – It conducts national surveys on socio-economic issues.
Sarvekshana – Quarterly journal published by NSSO.
![]() |
Use Code STAYHOME200 and get INR 200 additional OFF
|
Use Coupon Code |
201 videos|195 docs|64 tests
|