Statistics - Chapter 2 - Collection of data
Purpose: Reach a sound a clear conclusion to a problem which is backed by facts. Ex. Government when formulating policies.
Sources of data
Primary Data
Secondary Data
Collected at source
Communication between investigator and respondent
Original data
Data is obtained in a raw form
It is reliable (since collected first hand)
It is suitable, since questions specific to the research could be asked.
Time consuming and expensive (not economical)
No special precautions or editing needs to be done as data was obtained specifically for the project itself.
Adopting data Collected by an agency or institution which already collected the data through statistical surveys.
Sources include: published journals, magazines, census, government documents, etc.
No direct communication between Investigator and respondent
Not Original
Data is obtained in a finished form (tabulated and presented)
Less reliable (not collected firsthand)
Less Suitable (may not represent exactly what was being researched by the investigator)
Quick and easy (economical)
Special Precautions and editing needs to be done since the data was collected for a different purpose.
Definitions:
Investigator: One who conducts the investigation and seeks information. It can be an individual or organization.
Investigation: Statistical enquiry
Enumerators: They help the investigators in the collection of data. (assistants)
Informant / Respondent: They are the respondents who supply information to the investigator or enumerators. (people being surveyed)
Methods of collection of Primary Data:
Direct personal investigation
Indirect Oral Interview
Telephonic Interview
Information through correspondent
Questionnaire filled by enumerator
Mailed questionnaire method
Direct personal investigation
The investigator personally visits the respondents to collect information or data.
Merits
Demerits
Precautions
Reliability and Original
Correspondent: Local agents trained to collect information from respondents
Indirect oral investigation
Merits
Demerits
Information through correspondents
Questionnaire filled by Enumerator
Mailed Questionnaire Method
Telephonic Interview
Flexibility
Additional Information
Not suitable for wide area
Time-consuming
Expensive
Personal Bias
Social, laborious and experienced investigator
Well-versed in language, trade and customs
Limited number of questions
No personal bias
Establish a relationship (rapport)
The interviewer interviews several other people who are directly or indirectly in touch with the informants.
Wide coverage
Economical
Indirect information (less accurate)
Lack of Accuracy
Lack of uniformity
Possibility of bias to suit personal interests
Local agents or correspondents are appointed and trained to collect information from the respondents.
Merits
Demerits
Wide coverage
Time-saving
Suitable for special-purpose investigations
Continuity
Lack of uniformity
Lack of reliability
Personal Bias
Expensive
Lack of accuracy
Data is collected by an interviewer over the telephone.
Merits
Demerits
Wide area coverage
Time saving
Economical
Reliable
Limited use (Low accessibility - Only people with phones can be interviewed)
Visual feedback is not possible
An enumerator personally visits the informants with a questionnaire, asks questions and notes down responses in his own language.
A questionnaire containing a number of questions relating to the investigation is prepared. It is sent to the informants by post along with instructions on how to fill it. After filling out the questionnaire, the informant sends it back to the investigator.
Merits
Demerits
Wide coverage
Economical
Originality
Free from bias
Maintains secrecy as it filled out anonymously
Limited Accessibility
Low response (due to lack of interest)
Time consuming
Chance of misinterpretation
Merits
Demerits
Reliable and original
Better response (than mailed questionnaire method)
Useful in case of illiterate respondents
Expensive
Time consuming
Inefficiency
Personal Bias