Collection of Data

Statistics is the science which deals with the collection, organisation, analysis and interpretation of the numerical data.

Collection and analysis of numerical data is essential in studying many problems such as the problem of economic development of the country, educational development, the problem of health and population, the problem of agricultural development.

In any field of investigation, the first step is to collect the data. It is this data that will be analysed by the investigator or the statistician to draw inferences. It is of utmost importance that this data be reliable and relevant and collected according to a plan or design which must be laid out in advance.

Data are said to be primary if the investigator himself is responsible for the collection of data. Some examples of primary data are: voters’ lists, data collected in census-questionnaire.

It is not always possible for an investigator to collect data due to lack of time and resources. In that case, he or her may use data collected by other governmental or private agency in the form of published reports. This is called secondary data.

Data may be primary for one individual or agency but it becomes secondary for other using the same data. Since this data is collected for a purpose other than that of the original investigators, the user may lose some details or the data may not be all that relevant to his or her study. Therefore, such data must be used with great care.