Information from Correspondents - Methods of Primary Data Collection

The investigator appoints local agents or correspondents in different places to collect information under this method. These correspondents collect and transmit the information to the central office where data are processed. This method is generally adopted by news paper agencies.

Correspondents who are posted at different places supply information relating to such events as accidents, riots, strikes, etc., to the head office. The correspondents are generally paid staff or sometimes they may be honorary correspondents also. This method is also adopted generally by the government departments in such cases where regular information is to be collected from a wide area. For example, in the construction of a wholesale price index numbers regular information is obtained from correspondents appointed in different areas. The biggest advantage of this method is that, it is cheap and appropriate for extensive investigation. But a word of caution is that it may not always ensure accurate results because of the personal prejudice and bias of the correspondents.

As stated earlier, this method is suitable and adopted in those cases where the information is to be obtained at regular intervals from a wide area.

Indirect Oral Interviews - Methods of Primary Data Collection

Under this method of data collection, the investigator contacts third parties generally called ‘witnesses’ who are capable of supplying necessary information. This method is generally adopted when the information to be obtained is of a complex nature and informants are not inclined to respond if approached directly. For example, when the researcher is trying to obtain data on bribe or the habit of taking liquor, there is high probability that the bribed / addicted person will not provide the desired data and hence will disturb the whole research process. In this situation taking the help of such persons or agencies or the neighbours who know them well becomes necessary. Since these people know the person well, they can provide the desired data. Enquiry Committees and Commissions appointed by the Government generally adopt this method to get people’s views and all possible details of the facts related to the enquiry.

Though this method is very popular, its correctness depends upon a number of factors such as
1. The person or persons or agency whose help is solicited must be of proven integrity; otherwise any bias or prejudice on their part will not bring out the correct information and the whole process of research will become useless.
2. The ability of the interviewers to draw information from witnesses by means of appropriate questions and cross-examination.
3. It might happen that because of bribery, nepotism or certain other reasons those who are collecting the information give it such a twist that correct conclusions are not arrived at.

Therefore, for the success of this method it is necessary that the evidence of one person alone is not relied upon. Views from other persons and related agencies should also be ascertained to find the real position. Utmost care must be exercised in the selection of these persons because it is on their views that the final conclusions are reached. 

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Direct Personal Interviews - Methods of Primary Data Collection

A face to face contact is made with the informants (persons from whom the information is to be obtained) under this method of collecting data.

The interviewer asks them questions pertaining to the survey and collects the desired information. Thus, if a person wants to collect data about the working conditions of the workers of the BHEL, Trichy, he would go to the factory, contact the workers and obtain the desired information. The information collected in this manner is first hand and also original in character.

There are many merits and demerits of this method, which are discussed as under:

Merits:

1. Most often respondents are happy to pass on the information required from them when contacted personally and thus response is encouraging.

2. The information collected through this method is normally more accurate because interviewer can clear doubts of the informants about certain questions and thus obtain correct information. In case the interviewer apprehends that the informant is not giving accurate information, he may cross-examine him and thereby try to obtain the information.

3. This method also provides the scope for getting supplementary information from the informant, because while interviewing it is possible to ask some supplementary questions which may be of greater use later.

4. There might be some questions which the interviewer would find difficult to ask directly, but with some tactfulness, he can mingle such questions with others and get the desired information. He can twist the questions keeping in mind the informant’s reaction. Precisely, a delicate situation can usually he handled more effectively by a personal interview than by other survey techniques.

5. The interviewer can adjust the language according to the status and educational level of the person interviewed, and thereby can avoid inconvenience and misinterpretation on the part of the informant.

Demerits:

1. This method can prove to be expensive if the number of informants is large and the area is widely spread.

2. There is a greater chance of personal bias and prejudice under this method as compared to other methods.

3. The interviewers have to be thoroughly trained and experienced; otherwise they may not be able to obtain the desired information. Untrained or poorly trained interviewers may spoil the entire work.

4. This method is more time taking as compared to others. This is because interviews can be held only at the convenience of the informants. Thus, if information is to be obtained from the working members of households, interviews will have to be held in the evening or on week end. Even during evening only an hour or two can be used for interviews and hence, the work may have to be continued for a long time, or a large number of people may have to be employed which may involve huge expenses.

Though there are some demerits in this method still we cannot say that it is not useful. The matter of fact is that this method is suitable for intensive rather than extensive field surveys. Hence, it should be used only in those cases where intensive study of a limited field is desired.
In the present time of extreme advancement in the communication system, the investigator instead of going personally and conducting a face to face interview may also obtain information over telephone. A good number of surveys are being conducted every day by newspapers and television channels by sending the reply either by e-mail or SMS. This method has become very popular nowadays as it is less expensive and the response is extremely quick. But this method suffers from some serious defects, such as (a) those who own a phone or a television only can be approached by this method, (b) only few questions can be asked over phone or through television, (c) the respondents may give a vague and reckless answers because answers on phone or through SMS would have to be very short.

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Methods of Collecting Primary Data

Primary data refers to original data that has been collected from the original source first hand. Data collected this way is called primary data. It may be obtained by applying any of the following methods:

1. Observation.     
2. Direct Personal Interviews.       
3. Indirect Oral Interviews.      
4. Information from Correspondents.      
5. Mailed Questionnaire Methods.      

6. Schedule Sent Through Enumerators.

Important properties of the Normal distribution

The normal distribution was first described by Abraham Demoivre (1667-1754) as the limiting form of binomial model in 1733. Normal distribution was rediscovered by Gauss in 1809 and by Laplace in 1812. Both Gauss and Laplace were led to the distribution by their work on the theory of errors of observations arising in physical measuring processes particularly in astronomy. Here I will show you some important properties of Normal distribution

1. The normal curve is “bell shaped” and symmetrical in nature. The distribution of the frequencies on either side of the maximum ordinate of the curve is similar with each other.

2. The maximum ordinate of the normal curve is at. Hence the mean, median and mode of the normal distribution coincide.

3. It ranges between to

4. The value of the maximum ordinate is

5. The points where the curve change from convex to concave or vice versa is at

6. The first and third quartiles are equidistant from median.

7. The area under the normal curve distribution are:

a. covers 68.27% area

b. covers 95.45% area

c. covers 99.73% area

8. When μ = 0 and σ = 1, then the normal distribution will be a standard normal curve. The probability function of standard normal curve is

The following table gives the area under the normal probability curve for some important value of Z.

Distance from the mean ordinate in Terms of ± σ	Area under the curve
Z = ± 0.6745	0.50
Z = ± 1.0	0.6826
Z = ± 1.96	0.95
Z = ± 2.00	0.9544
Z = ± 2.58	0.99
Z = ± 3.0	0.9973

9. All odd moments are equal to zero.

10. Skewness = 0 and Kurtosis = 3 in normal distribution.

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International Conference on Advanced Management on February 2018

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Some Key Abbreviations used in Statistics

FNR - False Negative Ratio
FPR - False Positive Ratio
iff  - if an only if
I.I.d. - independent and identically distributed
IRQ - inter-quartile range
pdf - probability density function
LSE - Least Square Error
ML - Maximum Likelihood
MSE - Mean Square Error
PDF – probability distribution function
RMS - Root Mean Square Error
r.v. - Random variable
ROC - Receiver Operating Characteristic
SSB - Between-group Sum of Squares
SSE - Error Sum of Squares
SSLF - Lack of Fit Sum of Squares
SSPE - Pure Error Sum of Squares
SSR - Regression Sum of Squares
xxiv - Symbols and Abbreviations
SST - Total Sum of Squares
SSW - Within-group Sum of Squares
TNR - True Negative Ratio
TPR - True Positive Ratio
VIF - Variance Inflation Factor

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