Monthly Archives: December 2017

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 …

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 …

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 …

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 …

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 …