What is the difference between primary data and secondary data?

            Research is now a pervasive tool for business and studies with practical applications in nearly all fields. At the core of an investigation is data collection where a researcher must utilize the correct data source—primary or secondary data. This article explains the differences between these data sources.
            When researchers gather data for use in answering a specific problem at hand, this data is termed as primary data and is collected first hand. An example of this is a researcher who interviews people affected by a phenomenon such as a hurricane and tabulates the outcome for further analysis. Apart from being first-hand data, primary data is more accurate in answering a research question and often in crude form. The process of gathering primary data is expensive and time-consuming as compared to secondary data. Examples of primary data include surveys, questionnaires, and interviews.
            Secondary data refers to existing data collected in the past and available for use in subsequent research work or inquiry. This data is not suitable for use as the basis of answering a research problem but can serve as a supplement. A researcher can get quick access to secondary data as it may involve evaluation of government publications, journals, and organizations’ internal records among others. Secondary data is available in a refined form and omits all details of the initial research and thus less accurate than secondary data. Nonetheless, secondary data is less expensive than primary data as a researcher does not need to conduct costly tasks like interviews or observations.  
 
Further reading;
https://keydifferences.com/difference-between-primary-and-secondary-data.html
http://smallbusiness.chron.com/difference-between-primary-secondary-data-comes-market-research-56312.html
 
 
             
           
 

In research there are several methods used for data collection, which fall into two categories: primary data and secondary data. The difference between both are explained below:
Primary data:
Primary data is obtained for the first time by the researcher through direct efforts and their experience. Primary data can be collected through various sources like surveys, observations, experiments, questionnaires, personal interviews, telephone interviews, case studies, etc. Primary data collection is quite expensive, as the research is conducted by the organization itself, which requires huge investment. However, the data collection is under the direct control and supervision of the investigator specifically for the purpose of addressing their research problem.

Secondary Data:
Secondary data is the secondhand information or a third-party information which is already collected and recorded by persons other than the user. It is the readily available form of data collected from various sources like census, government publications, reports, books, journals, articles, websites, etc. Secondary data saves time and cost of the researcher since it is already available. But there are some disadvantages associated with this, as the objective and the method used for acquiring data may not be suitable to the current research problem. Therefore, before using secondary data, these factors should be kept in mind.