Internal source of information are that which come from data and statistics that are personally owned by the company. Internal information may take the form of sales figures, personnel records, customer records, and financial documents such as trading, profit and loss accounts and the balance sheet.
External information is which comes from outside the business. This is gathered via mainly secondary information methods such as newspapers and magazines, the internet etc.
External Source of information:
External source of information is what information has been collected by one organisation and then re-used for the same reason by the second organisation. For example, if a government department has conducted a survey of, say, family food expenditures, and then a food manufacturer might use that data in the organisation's evaluations of the total potential market for a new product.
No marketing research study should be undertaken without a prior search of secondary sources (also termed desk research). There are several grounds for making such a bold statement.
External sources of information can yield more accurate data than that obtained through primary research. This is not always true but where a government or international agency has undertaken a large scale survey, or even a census, this is likely to yield far more accurate results than custom designed and executed surveys when these are based on relatively small sample sizes.
External source of information can be extremely useful both in defining the population and in structuring the sample to be taken. For instance, government statistics on a country's agriculture will help decide how to stratify a sample and, once sample estimates have been calculated, these can be used to project those estimates to the population.
External source may be available which is entirely appropriate and wholly adequate to draw conclusions and answer the question or solve the problem.
It is far