Data Collection

Introduction

First step in statistical approach to a problem is the collection of numerical information i.e. data. Actually data are the raw materials for final statistical conclusions. In statistics , the main resource is the data . To start any statistical work, we need information. These information are data. Generally data can either be quantitative or qualitative . The data, which can be counted in natural way, is known as quantitative data where as the data, which represent some quality of an individual, is known as qualitative data . Generally , all collected phenomena are information and the the process which go through is called data collection .And it is being ready to use , for the purpose of statistical analysis , then it works as a data.

Types of  Data

1. Primary Data

Primary data are those fresh and original data, which are collected and recorded by the investigator or researcher. They are the first hand data. Primary data ate collected for specific purpose of study of the investigator or researcher. The source of this type of data is called primary source.

Methods of collecting Primary Data

1. Direct personal interview method
2. Indirect oral interview method
3. Information through correspondence
4. Mailed questionnaire method
5. Schedule sent through enumerators 

1. Direct personal interview method
In this method, the investigators or researchers meet the respondents personally and asked the necessary question and extract the required data from them. Since the researcher collects the information, the information is accurate , fresh and reliable.
Researcher can collect additional information if he or she needs. This method is effective for small number of respondents.

This method is suitable in the following situations.

• when the area of inquiry is limited
• when the data is to be kept secret
• when pure and original data is needed
• when the personal interviews by the investigator is essential 

Merits

• Information obtained by using this method is generally accurate.
• This is a flexible method in the sense that an investigator can make changes in questions if he or she feel to change
• Investigator can collect other supplementary information related with the study
• The accuracy of data can be verified in the spot since the investigator is being involved in collecting data

Demerits

• It is not useful for the wider area of inquiry
• There is chance of getting biased information
• It is expensive method

Precautions

• investigator must adopt high degree of accuracy and politeness
• personal discretion of the investigator should be avoided
• investigator should be familiar with the locality , language and culture where the data are collected etc.

 2. Indirect oral interview method
     
This method is applied in the situation when the informants hesitate to provide information directly . Information regarding the property , personal habits such as smoking habits, drug addicts, using family planning measures etc. In this method, information can generally be collected with the help of third person who is well known and familiar with the respondents.

It is suitable

• when the direct source of information are not available
• when the informants ate reluctant to give information

Merits

• this method is comparatively economic
• it is convenient way of gathering sensitive information with the help of witness
• it is applicable for wider area of inquiry
• information can e collected in speedy manner if appropriate witness is chosen

Demerits

• it is likely to get inaccurate and unreliable information
• the witness may be biased to provide accurate information.he or she may exaggerate the information
• there will be lack of interest for the witness to provide information about the respondents

Precautions

• the investigator must have confidence in the ability of the informants
• any kind of prejudice on the part of witness should be removed etc

 3. Information through correspondence
         
    This is a correspondence method. In this method, the investigator appoints the correspondence in different places to collect information .The correspondents collect information and send to the central office and finally central office utilizes the data .
This method is more suitable in the field of news media.

Merits

• this method is economic
• the information collected through this method is accurate
• the information from wide area can be easily obtained

Demerits

• information through this method may not be uniform
• it is time-consuming method if there is no facility of communication as telephone, internet etc.

4. Mailed questionnaire method

A set of questions is prepared and is known as questionnaire. The questionnaire is sent to the address of respondents by post. The respondents are requested to answer these questions and return to the investigator. This is suitable for educated informants . If one is interested to obtain the information from the graduates of Tribhuvan   University , Faculty of management , this method will be adopted. The contact address of such students is available in the office of controller of examination.

This method is suitable

• when the respondents are educated
• when the field of investigation is large
• when the address of respondents are available

Merits

• it is very economic method
• this method is suitable for wide sphere area of investigation

Demerits

• there is high degree of non-response error
• informants may feel fear to provide information
• informants may feel the complexity of question

Precautions

• questions should be simple 
• the object of inquiry should be clearly defined
• questions should not affect the personal feelings of informants etc.

5.  Schedule sent through enumerators
         Schedule is a list of questions on which the enumerators have to collect and record information. The enumerators fill it in. In this method, the investigators collect data through trained enumerators. This method is more useful when the informants are illiterate.

Merits

• it is suitable method in wide area of inquiry
• it is an accurate method of data collation
• non-response error will be minimized in this method

Demerits

• this is a time consuming method
• it is expensive method
• there is very few chance of being enumerator biased

Precations

• questions should be simple, clear and precise
• enumerators must be trained properly for the purpose
• enumerators should be capable and efficient etc

Steps followed in collecting Primary Data

1. planning the study
2. preparation of schedules or questionnaire
3. selection of the sample
4. editing the schedules

1.  planning the study
          for proper planning, the attention should be directed to the following points

• reviewing the earlier work
• scope of study
• determination of statistical units
• method of data collection
• units of measurement and degree of accuracy

2. Preparation of schedules or questionnaire
           there are no hard and fast rule for preparing questionnaire . however, the following are certain points which one should keep in mind while preparing questionnaire.

• clarity  = the questions should be clear and simple. the ambiguous and confusing questions are avoided.
• definiteness and objectivity = the questions should be formulated in such a way that they have a definite and objective answer
• numbers and arrangements of questions =  as much as possible,the number of questions should be small and questions should be arranged coherently.

3. selection of the sample
          samples are selected in such a way that they are  supposed to be representative of the whole population. details about the sampling procedure are discussed in sampling chapter.


4.  editing the schedules
         editing is the process of examining errors and omissions in the collected data and making necessary  corrections in the same. after receiving the filled up schedules, one should follow certain preparatiory measures before tabulation and statistical analysis is carried out.


Problems Involved in Collecting Primary Data
      There are various problems that have to be faced while collecting primary data. The nature of problems  depend upon the different situations. Some of the problems are follows

• generally there is lack of time and money while collecting primary data
• there is high degree of non-response error from illiterate respondents
• there may be lack of expertise and trained manpower for preparing questionnaire and collecting primary data.
• there is chance of getting unreliable data in some situations because of biasness of the enumerators.

Secondary Data
        Any data that have been collected earlier for some purpose are secondary data for the individuals who are using them. The data is a primary for those persons or institutions that collect them but the same data become secondary for another. Actually secondary data are the data, which are borrowed from
other who have collected them for some other purpose.

Advantage

• it saves time and cost
• if specially trained persons collect it , the quality of secondary data is better
• the scope of inquiry can be increased in terms of area and time period to  be covered

Disadvantage

• many a times the exact definition of terms and units used  in a secondary data are not known
• when the secondary  data are obtained from two source , it may not be comparable in terms of definitions , units and time period covered
• some information  is often omitted or some categories are pooled

Precaution in using secondary data

Reliability of Data
       The  investigator  should be very careful about the reliability of data. If data are not reliable , even it is treated and interpreted properly it may not give good result. It means that the result may miss guide .

Suitability of Data
       Even if the data are reliable , it should be used after confirming its suitability . It is essential to see whether the collected data are suitable for the purpose of inquiry or not. In this case, the investigator should compare the objectives , nature and scope of the given inquiry with the original investigation.


Adequacy of Data
        Even if the data are reliable and suitable , it is necessary to see whether it is adequate or not for the inquiry. Thus,  in order to arrive at conclusion free from limitations and accuracies, the secondary data must be subjected to through scrutiny and editing before they are accepted for use.


Difference between Primary and Secondary Data

Primary Data

• primary data are original in the sense that they are personally collected by the investigator  involving himself/'herself.
• primary data collection is more expensive and exhaustive
• primary data are collected as per requirement of the investigator
• primary data ma be influenced by personal prejudice of the investigator etc

Secondary Data

• Secondary Data are not original in the sense that they are collected  by some one other than the investigator 
• Secondary Data   are readily available at less expensess
• Secondary Data might have been collected with different objectives
• Secondary Data  may not be influenced by personal prejudice of the investigator etc.